- move shader flags from the video drivers to the context drivers
- rework config_load_shader_preset() from configuration.c into retroarch_load_shader_preset() in retroarch.c with proper compatibility check
- implicitly call retroarch_load_shader_preset() in retroarch_get_shader_preset() once per core/content life cycle
- use video_shader_is_supported() instead of video_driver_test_all_flags() where appropriate
- remove GFX_CTX_FLAGS_NONE because it is meaningless
Added a platform parameter to egl_init_context. If the caller provides a
platform other than EGL_NONE, then it will try to use eglGetPlatformDisplay or
eglGetPlatformDisplayEXT instead of eglGetDisplay.
If neither eglGetPlatformDisplay or eglGetPlatformDisplayEXT is supported, then
it will still fall back to calling eglGetDisplay.
Updated the Wayland, X11, and DRM callers to use the correct platform enum.
Those are the callers that don't just pass EGL_DEFAULT_DISPLAY as the native
display handle.
Calling eglGetDisplay with any value other than EGL_DEFAULT_DISPLAY is
inherently unreliable, because it requires the EGL implementation to guess a
platform type based on a (void *) pointer. Some implementations might not
identify a particular platform, or worse, might guess wrong.
Fixes https://github.com/libretro/RetroArch/issues/4790
