gl: avoid deadlock querying for OpenGL context
If there are two elements and threads attempting to query each other for an OpenGL context. The locking may result in a deadlock.
We need to unlock each element's context_lock when querying another element for the OpenGL context in order to allow any other element to take the lock when the other element is querying for an OpenGL context.
Depends on:
Edited by Sebastian Dröge