Fix bugs

[heyx3]

My other branch had too much stuff going on, sorry about that.

I made this branch to focus on the important and simpler problems, with missing constants and the bugged GLsizei.

[heyx3]

Reposting what I mentioned in the previous PR about GLsizei, for reference:

The errors I saw related to GLsizei being 64-bit instead of 32-bit was that any time i passed in a pointer to GLsizei, for OpenGL to tell me the length of something (e.x. a uniform name string, or an error log string), it would sometimes return a ridiculously large size, on the order of hundreds of billions.

It was extremely infrequent when getting uniform names, but happened every time when trying to read the error log. And it hasn't happened since changing the definition of GLsizei.

[SimonDanisch]

Thank you!