- Add variants of IsNonPragmaNonMacroLexer to accept an IncludeMacroStack entry
  (simplifies some uses).
- Use IsNonPragmaNonMacroLexer in Preprocessor::LookupFile.
- Add 'FileID' to PreprocessorLexer, and have Preprocessor query this fileid
  when looking up the FileEntry for a file

Performance testing of -Eonly on Cocoa.h shows no performance regression because
of this patch.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59666 91177308-0d34-0410-b5e6-96231b3b80d8