MSQOGL: fix black screen. Pointer functions must coming from Qt and its...

MSQOGL: fix black screen. Pointer functions must coming from Qt and its context. In multithreading, the initialization of filter is not always happening at the same time as Qt. So we must synchronize the initialization of the pointer later. Revert default functions initialization from ogl_display instantiation because it is too dangerous to load function pointers from the incorrect library/context.