meson: stop building XA by default

Commit cf40099730c4 ("meson: deprecate gallium-xa") deprecated XA
tracker, but didn't disable it by default. Thus any attempt to disable
it would cause a deprecated option warning. Flip the default to disable
XA tracker by default.

Fixes: cf40099730c4 ("meson: deprecate gallium-xa")
Backport-to: 25.1
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35113>
1 file changed