use proc.communicate() instead of wait() to prevent deadlock

Author: hathach

build_platform.py

@@ -336,9 +336,8 @@ def test_examples_in_folder(folderpath):
         proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE)
         try:
-            r = proc.wait(timeout=60)
-            out = proc.stdout.read()
-            err = proc.stderr.read()
+            out, err = proc.communicate(timeout=60)
+            r = 0
         except:
             proc.kill()
             out, err = proc.communicate()