fix bug [2021677] egl driver unloaded after eglTerminate() is called

refactored the code so that:
- EGL APIs that can be called before or after eglInitialize() will work by loading the drivers first
- make eglGetDisplay() a lot more efficient
- make sure that EGL drivers are loaded in a thread-safe way
- don't unload the drivers upon calling eglTerminate(), they're now never unloaded, since there is no safe way to do it (some thread could be running)
- updated our EGL version to 1.4
- return better error codes if errors happen during initialization