meson: disable -Werror=thread-safety on FreeBSD
Fixes #4333 (closed). Annotating properly is non-trivial and pointless unless FreeBSD is run on CI.
CC @unrelentingtech, @manu
Fixes #4333 (closed). Annotating properly is non-trivial and pointless unless FreeBSD is run on CI.
CC @unrelentingtech, @manu