ENH: Moved GetSourceFileLanguage up to cmLocalGenerator.

Source/cmLocalGenerator.h

@@ -172,6 +172,9 @@ public:
   /** Get the include flags for the current makefile and language.  */
   void GetIncludeDirectories(std::vector<std::string>& dirs);
 
+  /** Compute the language used to compile the given source file.  */
+  const char* GetSourceFileLanguage(const cmSourceFile& source);
+
   // Create a struct to hold the varibles passed into
   // ExpandRuleVariables
   struct RuleVariables