[preprocessor] In Preprocessor::CachingLex() check whether there were more tokens
cached during the non-cached lex, otherwise we are going to drop them.

Fixes a bogus "_Pragma takes a parenthesized string literal" error when
expanding consecutive _Pragmas in a macro argument.

Part of rdar://11168596

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153994 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed