[PATCH] isCharInSet refactoring.

[Alexander Kornienko]

  > (1) If the same ranges are used for two sets, they'll be validated twice. That's not so bad.

  Yes, it's not bad at all. We don't need to create many instances per one set of ranges.

  > (2) The Clang side now has static constructors. That's...kinda bad, right? I'm not sure what I want to do about it, though.

  I've replaced global static instances with local static variables in functions that use them. This will lead to creating two instances for some of the range sets, but the per-call overhead is still very low.

http://llvm-reviews.chandlerc.com/D1534