* [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

Currently assumes a single gamepad, has no code specific to gamepad
detection (gamepad is "detected" when an event related to gamepad
arrives). Also assumes that all gamepads look roughly like an xbox/ps
controller. Both assumptions are not strictly true, but an
implementation like that probably covers 85% of usecases.

Also it doesn't update previousButtonState so functions
IsGamepadButtonPressed() and IsGamepadButtonReleased() don't work, but
they didn't work previously on Android anyway, and they are flaky on
desktop as they are now, so the mechanism for these two functions
probably should be reworked anyway.

It's certainly an improvement compared to the previous android gamepad
handling code, which put gamepad events into touch related structs.

On android after rebinding context (which happens when you minimize and
navigate back to an app, or when you turn a screen off and back on)
there's a bug that viewport has a wrong scale and part of it is off
screen.

The change fixes it on devices I tried, but the solution feels hacky to
me. However when I attempted instead to call SetupViewport() again which
feels like a more proper solution, it didn't fix it.

Fix display -> screen coordinate conversion for android platform and
move it to the platform event handling code, simplifying
GetTouchPosition() function implementation.

Co-authored-by: Denis Pobedrya <denis.pobedrya@gmail.com>

Updated the list of projects that support 4.2

raylib library tries to avoid `long long` usage. Several SSBO functions have been reviewed (including some renames for consistency) to minimize `long long` type usage.

This simplification will allow the usage of `rshapes` as STANDALONE mode in a future. Only a small set of `rlgl` functions are required and they can be "more" easely replaced if no `rlPushMatrix()`/`rlPopMatrix()` are involved.

More simplification planned for the future, maybe the textures dependencies.

Updated version to `rlgl 4.2`

canJump used to alternate between true and false when on ground

* Update raylib.h

* CheckCollisionPointPolygon()

* typo

I want to note this is a special symbol exported

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!