If a window is being used for direct rendering with OpenGL or Vulkan, and is
using the flipping path for presentation, it's pixmap will be backed by a
dma-buf pixmap created by the client-side GL driver. However, this means that
xwl_glamor_eglstream_post_damage won't work since it requires that the pixmap
has an EGLSurface that it can render to, which dma-buf backed pixmaps do not.

The implication is that X rendering on a flipping OpenGL or Vulkan window isn't
possible with the eglstream backend. Currently, if an application tries to do
this, it will trigger an assert in xwl_glamor_eglstream_allow_commits. With
this commit, xwl_glamor_eglstream_allow_commits will instead just return false.

Signed-off-by: Erik Kurzinger <ekurzinger@nvidia.com>
Acked-by: Olivier Fourdan <ofourdan@redhat.com>