meson: link dri3 xcb libs into vlwinsys instead of into each target

meson: link dri3 xcb libs into vlwinsys instead of into each target

This makes the dependencies easier to manage, since each media target
doesn't need to worry about linking to half a dozen libraries.

Fixes: b1b65397d0c4978e3 ("meson: Build gallium auxiliary")
Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Acked-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>