[PATCH] Pull Lexer's CharInfo table out for general use throughout Clang

[Jordan Rose]

  We only get one more flag in CharInfo right now, although we could bump the table size up to a short. I don't think that it helps so much for $ since we'd end up doing the `AllowDollar` check //all// the time instead of just if the first check fails, but `isHexDigit` could definitely benefit from this.

  All other comments sound good; working on changes.

http://llvm-reviews.chandlerc.com/D363