meson: Move xvmc test tools from unit tests to installed tools.

These are not unit tests, as they rely on the host's XVMC and some user
configuration.  Switch them over to being general installed tools, to fix
unit testing.

Fixes: 22a817af ("meson: build gallium xvmc state tracker")
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
(cherry picked from commit 162fcdad)
Minor merge conflict resolved by Dylan

Conflicts:
	meson_options.txt