When creating the raw tokens for PTHLexer, make sure the token representing...

When creating the raw tokens for PTHLexer, make sure the token representing the file to include is checked for being an identifier.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59842 91177308-0d34-0410-b5e6-96231b3b80d8