Temporary preprocessor hack to get around the Microsoft __identifier(x) extension.

http://msdn.microsoft.com/en-us/library/hzc8ytsz(v=VS.100).aspx

Microsoft doc claims this is a C++/CLI feature but it is really always enabled.
This removes 2 error when parsing MFC code with clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131051 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Frontend/InitPreprocessor.cpp

@@ -343,6 +343,7 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
       // Since we define wchar_t in C++ mode.
       Builder.defineMacro("_WCHAR_T_DEFINED");
       Builder.defineMacro("_NATIVE_WCHAR_T_DEFINED");
+      Builder.append("#define __identifier(x) x");
       Builder.append("class type_info;");
     }
 

test/Parser/MicrosoftExtensions.cpp

@@ -207,3 +207,6 @@ __if_not_exists(IF_EXISTS::Type) {
 __if_not_exists(IF_EXISTS::Type_not) {
   int var244;
 }
+
+int __identifier(generic) = 3;
+