This reverts commit e190b7eee9.

* Add const qualifier to char * path argument
in qoa_open()

* Remove unnecessary cast

Some format tweaks

Switch to official `stb_vorbis.c` instead of using an outdated fork

* OpenGLES 2.0 support on PLATFORM_DESKTOP

* exmples raylib_opengl_interop desktop GLES2 support

* rename gles2.h -> glad_gles2.h

and make version check be only 150 not over 150

* fix issue #2728

* updated gamecontrollerdb: fixes GLFW warning due to invalid entry

* [rlgl] Check for extensions before enabling them

* Shift to glad on macOS

* #undef CORE_OPENGL_33

* Remove version hack and fix ASTC compression assumption

* Remove loader from glad

* Use GLAD_MALLOC/FREE instead of malloc/free

* More explicit extension checking

Reasons to NOT define `_GNU_SOURCE`:

 - access to lots of nonstandard GNU/Linux extension functions
 - access to traditional functions which were omitted from the POSIX standard (often for good reason, such as being replaced with better alternatives, or being tied to particular legacy implementations)
 - access to low-level functions that cannot be portable, but that you sometimes need for implementing system utilities like mount, ifconfig, etc.
 - broken behavior for lots of POSIX-specified functions, where the GNU folks disagreed with the standards committee on how the functions should behave and decided to do their own thing.

WARNING: This could be a BREAKING CHANGE for some platforms! I'm afraid something could be wrong on `rglfw.c` module.

To be able to compile on Windows I had to modify `glfw/src/platform.c` line 74. I couldn't manage to compile without that change, help is welcome!

* Win32: resolve some symbols re-definition of windows.h in glfw3native.h

This reflects GLFW's fix: https://github.com/glfw/glfw/issues/1348

This enables to build with a external GLFW containing the
following fix:

* 05f6c13d11

Currently, glfw3native.h of the internal GLFW is customized at
2feea87b61

This fix is compatible with the current customized glfw3native.h.

This fix enables us to update it to the latest and remove the
customization.

* Win32: remove unneeded typedef

This reverts commit d786af83fc.

* Updated QOI to latest version.

* Enable back QOI support!

* Stray extra space! Should be good now.