- video_shader_parse_type()'s fallback only worked for NULL paths and was wrongly used, now returns RARCH_SHADER_NONE like video_shader_get_type_from_ext().
- video_shader_get_type_from_ext() should not be checking video driver flags, this is instead done by video_shader_is_supported()
- video_driver_get_all_flags() did not actually 'get' flags, changed to video_driver_test_all_flags()
workaround for crash due to glcore not always using at least OpenGL 3.2