fix build paths

[hardliner66]

I figured out what the problem for #3834 was and found a solution to fix it as well.

The first problem was, that srcdir is an absolut path, but using .{.path = ...} is supposed to be relative only. So I instead changed it to use .cwd_relative which is badly named, but the appropriate field to use for absolute paths.

The next problem was, that the files added via addCSourceFilesVersioned needed to be relativ to the module (raylib itself) so I figured out a way to get the relative path and added that too.

Theres still a minor problem with getting the relative path, but that shouldn't take that long to fix.

[hardliner66]

Fixed the final problem as well. Raylib now compiles on it's own and inside my project without problesm.

[raysan5]

@hardliner66 Some experienced zig developer should review this change. I feel it adds an extra level of complexity, not sure if really required.

[hardliner66]

I mean, it really doesn't add that much complexity. Also, the build is broken without it, because Zig sometimes uses the absolute path as relative path and it can't find files anywhere.

The proper solution when 0.12 is stable would be to switch to use a build.zig.zon and make raylib a proper package, but right now I don't think that's a good move yet.

So the only way to do this is to fix the problem at hand. Only thing I might would want to change is to use join everywhere instead of string concatenation, but I wanted to introduce as little change as possible while still fixing the issue.

Alternatively we could require the user to pass the relative location to the addRaylib function, instead of figuring out ourselves, but that would break every user who currently uses this. So I maded it figure out the path properly in a way that wont break user code.

IIRC there are other projects having the same problem as I had when importing raylib and this should fix it for them as well. I will try to find them and paste them here as well.

[raysan5]

@hardliner66 Thanks for the detailed explanation. I'm merging it.

[hardliner66]

No problem. I analyzed the bug and fixed it, so I should also explain it. But yesterday it was already 2:30am when I created the MR, so my explanation skills weren't the best probably 😅