regex_impl: Fix a potential format string flaw
regex_impl: Fix a potential format string flaw

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