Replace re module by regex module in run-clang-tidy script

[sylvestre.ledru]

Summary

Avoid limitation of 100 groups for regular expressions
Patch by Manuel Grizonnet

reported here:
https://github.com/llvm-mirror/clang-tools-extra/pull/9

[alexfh]

https://docs.python.org/2/howto/regex.html#introduction says "The regex module was removed completely in Python 2.5.". Why would we want to switch to it?

[alexfh]

Actually, I'm not sure why we need groups in that regex. We can instead try replacing re.compile('(' + ')|('.join(args.files) + ')') with re.compile('|'.join(args.files)).

[sylvestre.ledru]

done here: r298619

clang-tidy/tool/run-clang-tidy.py

 import multiprocessing
 import os
 import Queue
-import re
+import regex as re
 import shutil
 import subprocess
 import sys