virgl/ci: Prevent static link of virglrenderer inside crosvm

virgl/ci: Prevent static link of virglrenderer inside crosvm

Ensure virglrenderer library is built before crosvm in order to allow
dynamic linking. This is needed for the scenarios where a different
virglrenderer library must be provided before launching crosvm, e.g.:
the upcoming Virgl CI solution that shares Mesa CI containers.

Additionally, this provides the virgl_test_server binary which is
required by piglit-runner.sh and deqp-runner.sh scripts when using
the virpipe Gallium driver.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Rohan Garg <rohan.garg@intel.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14413>