meson: Do not enable USE_ELF_TLS for FreeBSD

Compiling with this option result in too much TLS usage and FreeBSD
cannot handle that.

Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Signed-off-by: Emmanuel <manu@FreeBSD.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3559>
1 file changed