meson: add a warning for meson < 0.46.0

This could help somebody to be noticed about meson issue:
https://github.com/mesonbuild/meson/pull/3274
as result NDEBUG won't be defined even if b_ndebug is true
and buildtype is release.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109791


Cc: mesa-stable@lists.freedesktop.org
Acked-by: Eric Engestrom <eric.engestrom@intel.com>
Signed-off-by: Andrii Simiklit <andrii.simiklit@globallogic.com>