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
This flag is obsolete.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.
