patch 9.2.0484: TextPutPre triggers clipboard provider callback twice

patch 9.2.0484: TextPutPre triggers clipboard provider callback twice

Problem:  TextPutPre triggers clipboard provider callback twice
          when do_put() runs autocommands that themselves request
          the clipboard.
Solution: Guard do_put() and put_do_autocmd() with
          inc_clip_provider()/dec_clip_provider() so the provider
          is queried at most once per put operation (Foxe Chen).

closes: #20215

Signed-off-by: Foxe Chen <chen.foxe@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>