Add initialization of static bindings for egl and glx

Use lazy binding for static bindings initialization, the
same way we do in ozone.

Task-number: QTBUG-65682
Change-Id: I51ecdfa3b7daca8b1345cf2c0c89a4ac6e25a7c9
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>