Implement #pragma redefine_extname.

This fixes PR5172 and allows clang to compile C++ programs on Solaris using the system headers.

llvm-svn: 150881
diff --git a/clang/lib/Parse/ParsePragma.h b/clang/lib/Parse/ParsePragma.h
index 1d3138f..ebb185a 100644
--- a/clang/lib/Parse/ParsePragma.h
+++ b/clang/lib/Parse/ParsePragma.h
@@ -90,6 +90,16 @@
                             Token &FirstToken);
 };
 
+class PragmaRedefineExtnameHandler : public PragmaHandler {
+  Sema &Actions;
+public:
+  explicit PragmaRedefineExtnameHandler(Sema &A)
+    : PragmaHandler("redefine_extname"), Actions(A) {}
+
+  virtual void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                            Token &FirstToken);
+};
+
 class PragmaOpenCLExtensionHandler : public PragmaHandler {
   Sema &Actions;
   Parser &parser;