On hybrid graphics system, the primary path used to transfer the stage
framebuffer onto the dedicated GPU's video memory preparing for scanout,
is using the dedicated GPU to glBlitFramebuffer() the content from the
iGPU texture onto the scanout buffer.
After we have done this, we reset the current EGL context back to the
one managed by cogl. What we failed to do, however, was to reset the
current EGL context when we inhibited the actual page flip due to having
entered power save mode.
When we later started to paint again, Cogl thought the current EGL
context was still the correct one, but in fact it was the one used for
the iGPU -> dGPU blit, causing various EGL surface errors, and as a side
effect, eventually hitting an assert.
Fix this by making sure we reset to the Cogl managed EGL context also
for this case.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1803>
14f6869381