meson: add -Werror=empty-body to disallow `if(x);`
/cc @daenzer @jekstrand
This would have prevented !2058 (comment 237880); with that MR fixed, nothing else uses empty-body blocks, so let's just forbid them altogether.
/cc @daenzer @jekstrand
This would have prevented !2058 (comment 237880); with that MR fixed, nothing else uses empty-body blocks, so let's just forbid them altogether.