GstVaapiDecode is a descendant of GstVaapiMiniObject, so, thought we should
use its methods, even though it doesn't change functionality.
GstVaapiPixmap, GstVaapiTexture and GstVaapiWindow are descendant of
GstVaapiObject, hence its methods shall be used.
https://bugzilla.gnome.org/show_bug.cgi?id=772554
Add support for GstVideoGLTextureOrientation modes. In particular,
add orientation flags to the GstVaapiTexture wrapper and the GLX
implementations. Default mode is that texture memory is laid out
with top lines first, left row first. Flags indicate whether the
X or Y axis need to be inverted.
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.
GstVaapiTexture is a generic abstraction that could be moved to the
core libgstvaapi library. While doing this, no extra dependency needs
to be added. This means that a GstVaapitextureClass is now available
for any specific code that needs to be added, e.g. creation of the
underlying GL texture objects, or backend dependent ways to upload
a surface to the texture object.
Generic OpenGL data types (GLuint, GLenum) are also replaced with a
plain guint.
https://bugzilla.gnome.org/show_bug.cgi?id=736715
