Fix rdar://6562329, a static analyzer crash Ted noticed on

Fix rdar://6562329, a static analyzer crash Ted noticed on
wine sources.  This was happening because HighlightMacros was
calling EnterMainFile multiple times on the same preprocessor
object and getting an assert due to the new #line stuff (the
file in question was bison output with #line directives).

The fix for this is to not reenter the file.  Instead,
relex the tokens in raw mode, swizzle them a bit and repreprocess
the token stream.  An added bonus of this is that rewrite macros
will now hilight the macro definition as well as its uses.  Woo.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64480 91177308-0d34-0410-b5e6-96231b3b80d8