Add new generic helper functions gst_vaapi_texture_new_wrapped()
and gst_vaapi_texture_new() to create a texture without having
the caller to uselessly check for the display type himself. i.e.
internally, there is now a GstVaapiDisplayClass hook to create
textures, and the actual backend implementation fills it in.
This is a simplification in view to supporting EGL.
The VA/GLX interfaces are obsolete. They used to exist for XvBA, and
ease of use, but they had other caveats to deal with. It's now better
to move on to legacy mode, whereby VA/GLX interop is two be provided
through (i) X11 Pixmap, and (ii) other modern means of buffer sharing.
https://bugzilla.gnome.org/show_bug.cgi?id=736711
Make it possible to add extra an extra filter to most of display cache
lookup functions so that the GstVaapiDisplay instance can really match
a compatible and existing display by type, instead of relying on extra
string tags (e.g. "X11:" prefix, etc.).
Move display types from gstvaapipluginutil.* to gstvaapidisplay.* so that
we could simplify characterization of a GstVaapiDisplay. Also rename "auto"
type to "any", and add a "display-type" attribute.
