configure: fix build error with XA
Fixes: xa_tracker.c: In function 'xa_tracker_create': xa_tracker.c:147:5: error: implicit declaration of function 'pipe_loader_drm_probe_fd' [-Werror=implicit-function-declaration] in some build configurations, as XA now implicitly depends on gallium_drm_loader. Signed-off-by:Rob Clark <robclark@freedesktop.org> Reviewed-by:
Jakob Bornecrantz <jakob@vmware.com>