patch 9.1.1228: completion: current position column wrong after got a match

patch 9.1.1228: completion: current position column wrong after got a match

Problem:  The current_pos.col was incorrectly updated to the length of
          the matching text. This will cause the next search to start
          from the wrong position.
Solution: current_pos has already been updated in search_str_in_line and
          does not need to be changed (glepnir)

closes: #16941

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>