src: Propagate to clients the `kill` exit code
src: Propagate to clients the `kill` exit code

Fixes #2177

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