[JdkInfo] handle invalid XML from /usr/libexec/java_home (#120)

Context: dotnet/android#5992
Context: https://dev.azure.com/xamarin/public/_build/results?buildId=40929&view=logs&j=cfef19e4-4225-5e84-636a-86ba2231ac21&t=cd3bc6c3-ac29-5320-67c9-5fb59fc8e05c&l=732

dotnet/maui has hit some build failures such as:

	error XARSD7000: System.Xml.XmlException: Root element is missing.
	error XARSD7000:   at System.Xml.XmlTextReaderImpl.Throw (System.Exception e)
	error XARSD7000:   at System.Xml.XmlTextReaderImpl.ThrowWithoutLineInfo (System.String res)
	error XARSD7000:   at System.Xml.XmlTextReaderImpl.ParseDocumentContent ()
	error XARSD7000:   at System.Xml.XmlTextReaderImpl.Read ()
	error XARSD7000:   at System.Xml.XmlReader.MoveToContent ()
	error XARSD7000:   at System.Xml.Linq.XElement.Load (System.Xml.XmlReader reader, System.Xml.Linq.LoadOptions options)
	error XARSD7000:   at System.Xml.Linq.XElement.Parse (System.String text, System.Xml.Linq.LoadOptions options)
	error XARSD7000:   at System.Xml.Linq.XElement.Parse (System.String text)
	error XARSD7000:   at Xamarin.Android.Tools.JdkInfo+<GetLibexecJdkPaths>d__56.MoveNext ()
	error XARSD7000:   at System.Linq.Enumerable+DistinctIterator`1[TSource].MoveNext ()
	error XARSD7000:   at System.Linq.Enumerable+SelectEnumerableIterator`2[TSource,TResult].MoveNext ()
	error XARSD7000:   at System.Linq.Enumerable+WhereSelectEnumerableIterator`2[TSource,TResult].ToArray ()
	error XARSD7000:   at System.Linq.Buffer`1[TElement]..ctor (System.Collections.Generic.IEnumerable`1[T] source)
	error XARSD7000:   at System.Linq.OrderedEnumerable`1+<GetEnumerator>d__3[TElement].MoveNext ()
	error XARSD7000:   at System.Linq.Enumerable+ConcatIterator`1[TSource].MoveNext ()
	error XARSD7000:   at System.Linq.Enumerable+SelectEnumerableIterator`2[TSource,TResult].MoveNext ()
	error XARSD7000:   at Xamarin.Android.Tools.AndroidSdkBase.GetValidPath (System.Func`2[T,TResult] pathValidator, System.String ctorParam, System.Func`1[TResult] getPreferredPath, System.Func`1[TResult] getAllPaths)
	error XARSD7000:   at Xamarin.Android.Tools.AndroidSdkBase.Initialize (System.String androidSdkPath, System.String androidNdkPath, System.String javaSdkPath)
	error XARSD7000:   at Xamarin.Android.Tools.AndroidSdkInfo..ctor (System.Action`2[T1,T2] logger, System.String androidSdkPath, System.String androidNdkPath, System.String javaSdkPath)
	error XARSD7000:   at Xamarin.Android.Tasks.MonoAndroidHelper.RefreshAndroidSdk (System.String sdkPath, System.String ndkPath, System.String javaPath, Microsoft.Build.Utilities.TaskLoggingHelper logHelper)
	error XARSD7000:   at Xamarin.Android.Tasks.ResolveSdks.RunTask ()
	error XARSD7000:   at Xamarin.Android.Tasks.AndroidTask.Execute ()

It looks like `JdkInfo.GetLibexecJdkPaths()` doesn't handle
`XmlException` and warn appropriately.

I don't have the *actual* output of `/usr/libexec/java_home -X` from
these machines, but I suspect it's printing some message before the
XML or no XML at all.

Author: jonathanpeppers

src/Xamarin.Android.Tools.AndroidSdk/JdkInfo.cs

@@ -350,7 +350,14 @@ static IEnumerable<string> GetLibexecJdkPaths (Action<TraceLevel, string> logger
 						return;
 					xml.Append (e.Data);
 			}, includeStderr: false);
-			var plist   = XElement.Parse (xml.ToString ());
+
+			XElement plist;
+			try {
+				plist = XElement.Parse (xml.ToString ());
+			} catch (XmlException e) {
+				logger (TraceLevel.Warning, string.Format (Resources.InvalidXmlLibExecJdk_path_args_message, jhp.FileName, jhp.Arguments, e.Message));
+				yield break;
+			}
 			foreach (var info in plist.Elements ("array").Elements ("dict")) {
 				var JVMHomePath = (XNode) info.Elements ("key").FirstOrDefault (e => e.Value == "JVMHomePath");
 				if (JVMHomePath == null)

src/Xamarin.Android.Tools.AndroidSdk/Properties/Resources.Designer.cs

@@ -130,4 +130,7 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</comment>
   </data>
+  <data name="InvalidXmlLibExecJdk_path_args_message" xml:space="preserve">
+    <value>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</value>
+  </data>
 </root>

src/Xamarin.Android.Tools.AndroidSdk/Properties/Resources.resx

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.cs.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.de.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.es.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.fr.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.it.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>

src/Xamarin.Android.Tools.AndroidSdk/Properties/xlf/Resources.ja.xlf

@@ -17,6 +17,11 @@
 {0} - The path of the file being read.
 {1} - The exception message of the associated exception.</note>
       </trans-unit>
+      <trans-unit id="InvalidXmlLibExecJdk_path_args_message">
+        <source>An exception occurred while reading the output of '{0} {1}'. Exception: {2}</source>
+        <target state="new">An exception occurred while reading the output of '{0} {1}'. Exception: {2}</target>
+        <note />
+      </trans-unit>
     </body>
   </file>
 </xliff>