Improve check for display cache infrastructure. In particular, for X11 and
GLX backends, we need to make sure that we can create a GstVaapiDisplayX11
from another GstVaapiDisplayGLX, i.e. underlying X11 and VA displays can be
shared. Besides, allocating a GstVaapiDisplayGLX while a GstVaapiDisplayX11
already exists will have to generate different VA displays.
Use gst_vaapi_image_format_from_structure() helper in test-display and
then extract a VAImageFormat from it instead of relying on GstCaps for
YUV and RGB formats.
This flag is obsolete. It was meant to explicitly enable/disable VA/GLX API
support, or fallback to TFP+FBO if this API is not found. Now, we check for
the VA/GLX API by default if --enable-glx is set. If this API is not found,
we now default to use TFP+FBO.
Note: TFP+FBO, i.e. using vaPutSurface() is now also a deprecated usage and
will be removed in the future. If GLX rendering is requested, then the VA/GLX
API shall be used as it covers most usages. e.g. AMD driver can't render to
an X pixmap yet.
