Refcount mapping and unmapping of VABuffers.

On some 1080 movies the commit-id: 42be4519
gave issues. Reverting some parts of this commit solves this issue.

Cleanup all subpicture associations when freeing a surface.

The xvba-video wrapper used a local X11 connection. However this prevents
using overlays on the application provided X11 display to be shown.

When calling XOpenDisplay in vaInitialize, then also call XCloseDisplay in vaTerminate.

Explicitly enable/disable targets when using OpenGL code.

Add extra checking.

The API offered a gl_create_texture() but not and gl_destroy_texture().

The function query_surface_status_glx() changes the surface status. This looks
very suspicious and might be even a design error.

The render thread allocates a new render_context, but never destroys it
when shutting down. It possibly leaks on closing.

Do not leak subpicture associations, but rather crash so that the bug can be investigated and fixed.

- fix error path in create_hw_image_glx()

The boolean operator || requires an evaluation of both expressions.
If the expressions evaluates pointers, then care must be taken that
both expressions have valid pointer. In this case it cannot be guaranteed,
thus splitting the check is needed.

The boolean operator || requires an evaluation of both expressions.
If the expressions evaluates pointers, then care must be taken that
both expressions have valid pointer. In this case it cannot be guaranteed,
thus splitting the check is needed.

The location of an object in the heap was wrongly determined, by applying the HEAP_ID_MASK to the object id. Instead the heap->id_offset should have been substracted from the object id. The object id is created by using the i-th position plus heap->id_offset.

The boolean operator || requires an evaluation of both expressions.
If the expressions evaluates pointers, then care must be taken that
both expressions have valid pointer. In this case it cannot be guaranteed,
thus splitting the check is needed.

Remove association buffers if adding did not work properly.

Instead of aborting on an empty buffer we just continue, since the
buffer would be freed anyway on the next line. This patch makes the
function more tolerant.

The original install rule would fail if the link already existed.
Now installing succeeds if the destination was already there, it will
be overwritten with the new file.

The extern keyword is needed for instructing the linker to resolve
hw_image_hooks_glx, which is declared in another object. Failing to
do so results in an assert later on when using subpictures.