Merge "[get_clang_version] Make the version regex permissive"

  with open(global_go) as infile:

    contents = infile.read()

  regex_rev = r'\tClangDefaultVersion\s+= "(?P<rev>clang-r\d+[a-z]?\d?)"'

  regex_rev = r'\tClangDefaultVersion\s+= "(?P<rev>clang-.*)"'

  match_rev = re.search(regex_rev, contents)

  if match_rev is None:

    raise RuntimeError('Parsing clang info failed')