patch 9.2.0447: cindent does not ignore comments

patch 9.2.0447: cindent does not ignore comments

Problem:  When find_start_brace() scans backwards for the enclosing
          block, '{' and '}' inside // and /* */ comments are counted,
          producing wrong indent for code following such comments
          (rendcrx).
Solution: Implement FM_SKIPCOMM in findmatchlimit() to track block-
          comment state and skip matches inside comments. Pass
          FM_SKIPCOMM from cindent's call sites
          (find_start_brace, find_match_char, cin_iswhileofdo,
          get_c_indent).

fixes:  #4
fixes:  #648
fixes:  #19578
closes: #19581
closes: #20111

Signed-off-by: magnus-rattlehead <guranjakustivi@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>