meson.build: Add more compilation warnings

Use the same warnings as mutter.

GNOME/gnome-shell!441
4 jobs from build-warnings3 in 21 minutes and 59 seconds (queued for 1 minute and 11 seconds)
merge request
Status Job ID Name Coverage
  Review
passed #243634
check_commit_log

00:08:57

 
  Build
passed #243635
build

00:07:36

 
  Test
passed #243636
test

00:05:25

passed #243637
test-pot

00:00:57