resolve some C-preprocessor macros

[Brian-ED]

C macros cause errors if used for declaring functions and structs. It's rare, but rlgl.h in raylib does that.

My current idea on resolving this is having an argument for inputting if defines should be true or false and making a simple preprocessor for this purpose.

[Brian-ED]

I can use cpp -p but it would include other files and code elsewhere. It'd also remove definition macros that define variables like the RLGL_VERSION string.

[Brian-ED]

idea: remove #includes before calling cpp -p. Also find #defines before calling it.

[Brian-ED]

cpp -p -E -CC raylib.h > out.txt worked, for including comments in output

[Brian-ED]

#define's value might rely on an #include