[clang-tidy][NFC] Tweak GlobList to iterate backwards
By iterating backwards over the globs we can exit the loop as soon as we find a match.
While we're here:
- Regex doesn't need to be mutable.
- We can reserve the amount of Globs needed ahead of time.
- Using a SmallVector with size 0 is slightly more space efficient than a std::vector.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D91033