EGL brings in platform-specific headers such as the dreaded `windows.h`,
and `platform_gl.h` is used throughout `drivers/gles3` for basic OpenGL
types such as `GLuint`. We don't want `windows.h` pollution there.
Note for Android: EGL seems used explicitly only via `rasterizer_gles3.cpp`
to enable GL debug printing, and some custom stuff in `config.cpp`.
This will allow decoupling `display_server.h` from a number of headers in the
codebase which only require those enums and not all the DisplayServer API.
Thaddeus Crews
Rémi Verschelde
Allen Pestaluky
Stuart Carnie