clang-format: Understand #pragma mark

Before:
  #pragma mark Any non - hyphenated or hyphenated string(including parentheses).
After:
  #pragma mark Any non-hyphenated or hyphenated string (including parentheses).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@198870 91177308-0d34-0410-b5e6-96231b3b80d8