Use PushIncludeMacroStack() instead of manually manipulating the include stack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59181 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Lex/PPCaching.cpp

@@ -76,10 +76,7 @@ void Preprocessor::EnterCachingLexMode() {
   if (InCachingLexMode())
     return;
 
-  IncludeMacroStack.push_back(IncludeStackInfo(CurLexer, CurDirLookup,
-                                               CurTokenLexer));
-  CurLexer = 0;
-  CurTokenLexer = 0;
+  PushIncludeMacroStack();
 }