Honour meson warning level for flags
This is equivalent of a change made in libvirt.git a little while ago.
Essentially makes us only set extra warning flags if meson warning_level==2
The 17.0 major release is coming on May 16, 2024! This version brings many exciting improvements to GitLab, but also removes some deprecated features. We are introducing three breaking change windows during which we expect breaking changes to be deployed to GitLab.com. You can read more about it on our blogpost. The third breaking change window begins 2024-05-06 09:00 UTC and ends 2024-05-08 22:00 UTC.
This is equivalent of a change made in libvirt.git a little while ago.
Essentially makes us only set extra warning flags if meson warning_level==2