Frontend: Define __EXCEPTIONS if -fexceptions is passed

GCC defines __EXCEPTIONS, regardless of language mode, if -fexceptions
is passed.  We should do the same.

This fixes PR21358.

llvm-svn: 220714
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 802b2a9..476e214 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -550,7 +550,7 @@
     Builder.defineMacro("__BLOCKS__");
   }
 
-  if (!LangOpts.MSVCCompat && LangOpts.CXXExceptions)
+  if (!LangOpts.MSVCCompat && LangOpts.Exceptions)
     Builder.defineMacro("__EXCEPTIONS");
   if (!LangOpts.MSVCCompat && LangOpts.RTTI)
     Builder.defineMacro("__GXX_RTTI");