Fix compilation on older gcc / clang
Fix compilation on older gcc / clang

This was already fixed on the menu-completions branch but an previous
commit version was wrongly cherry-picked.

Fixes #2914

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