quartz: Reimplement AM_RENDEREX_RENDERTOEXISTINGRENDERERS by forbidding renderers from IFilterMapper2::EnumMatchingFilters().

Primarily to avoid unnecessarily creating filters like the VMR.
Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>