Use fork instead of vfork on CYGWIN
Use fork instead of vfork on CYGWIN

Fixes #2653

Somasis/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,lenormf/kakoune,jkonecny12/kakoune,mawww/kakoune,danr/kakoune,Somasis/kakoune,casimir/kakoune,occivink/kakoune,lenormf/kakoune,Somasis/kakoune,lenormf/kakoune,danr/kakoune,casimir/kakoune,alexherbo2/kakoune,alexherbo2/kakoune,mawww/kakoune,casimir/kakoune,occivink/kakoune,jkonecny12/kakoune,occivink/kakoune,casimir/kakoune,mawww/kakoune,danr/kakoune,Somasis/kakoune,lenormf/kakoune,alexherbo2/kakoune,occivink/kakoune,danr/kakoune,mawww/kakoune