Fix predicate: we're not in caching mode if CurPPLexer == 0, not CurLexer == 0.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59848 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Lex/Preprocessor.h

@@ -628,7 +628,7 @@ private:
   //===--------------------------------------------------------------------===//
   // Caching stuff.
   void CachingLex(Token &Result);
-  bool InCachingLexMode() const { return CurLexer == 0 && CurTokenLexer == 0; }
+  bool InCachingLexMode() const { return CurPPLexer == 0 && CurTokenLexer == 0;}
   void EnterCachingLexMode();
   void ExitCachingLexMode() {
     if (InCachingLexMode())