fix vdpau interop when using -Bsymbolic-functions in ldflags

fix vdpau interop when using -Bsymbolic-functions in ldflags

Explicitly add radeon_drm_winsys_create and nouveau_drm_screen_create to
the dynamic list. This will ensure vdpau interop still works even when
the user links with -Bsymbolic-functions in hardened builds.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Rachel Greenham <rachel@strangenoises.org>
Reported-by: Peter Frühberger <peter.fruehberger@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>