Update bindings

[hwsmm]

• Continuation of Update bindings 3 (no merging needed) #129

Feel free to take over maintaining if I look inactive here!

Relevant osu!framework branch

---

This bindings update is currently a bit janky mostly because of this PR that changes SDL_bool to bool entirely.

Applied workarounds:

• Add --language c in ClangSharp arguments because bool is C++ keyword, and re-define SDL_bool because C/C++ bool cannot be directly converted to C# bool.
• Add != NULL / == NULL to compare pointers in header functions as ClangSharp generated pointer && pointer comparison, which is not possible in C#, after --language c.
• Define NULL=0 as ClangSharp tried to put null in a variable of nint type after --language c.
• Define some constant macros of SDL_pixels.h in manually written code, as adding --language c made SDL_Colorspace macros to have int for some reason.

I will probably report those bugs over ClangSharp repository since upgrading it didn't help...

[Susko3]

I don't like the complexity increase here. Most of the bool issues can be solved with --remap bool=SDL_bool. The only errors then are in ClangSharp generated function bodies that try to convert bool to enum SDL_bool, which doesn't work. Better to make SDL_bool a struct with implicit bool conversions.

So I've made #147 instead.