use initializer lists for language file extensions

Author: Daniel Kroening

src/ansi-c/ansi_c_language.cpp

@@ -40,10 +40,7 @@ Function: ansi_c_languaget::extensions
 
 std::set<std::string> ansi_c_languaget::extensions() const
 {
-  std::set<std::string> s;
-  s.insert("c");
-  s.insert("i");
-  return s;
+  return { "c", "i" };
 }
 
 /*******************************************************************\

src/java_bytecode/java_bytecode_language.cpp

@@ -34,10 +34,7 @@ Function: java_bytecode_languaget::extensions
 
 std::set<std::string> java_bytecode_languaget::extensions() const
 {
-  std::set<std::string> s;
-  s.insert("class");
-  s.insert("jar");
-  return s;
+  return { "class", "jar" };
 }
 
 /*******************************************************************\

src/jsil/jsil_language.cpp

@@ -32,9 +32,7 @@ Function: jsil_languaget::extensions
 
 std::set<std::string> jsil_languaget::extensions() const
 {
-  std::set<std::string> s;
-  s.insert("jsil");
-  return s;
+  return { "jsil" };
 }
 
 /*******************************************************************\