c.zig: add sigfillset, alarm, sigwait

I've added these three functions to all switches except NetBSD, because I don't know what the function is named there. I've even added it on the .windows switch since all the posix functions seem to be there anyways.
1b3cc66334codic12 committed on 6/11/2021, 1:28:20 PM· committed by GitHubparent56c0a66
1 file changedLine totals unavailable