Do not add window pointing to deleted buffers in the free window list
Do not add window pointing to deleted buffers in the free window list

Fixes #2975

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