Make piping data into shell commands non blocking
Make piping data into shell commands non blocking

Fixes #1180

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