Add missing Darwin declarations

[danielchasehooper]

These types are necessary to use functions that are already pulled into c.zig from std/c/darwin.zig, like the mach_vm_*() functions.

I almost certainly didn't get all the missing pub declarations, these are just the ones I've needed for what I'm working on. Is there a better way to do this? Should c.zig's const darwin be pub? Should platform specific stuff get moved up a level to std.darwin/std.freebsd/etc files?

[andrewrk]

Thanks!

[andrewrk]

Is there a better way to do this? Should c.zig's const darwin be pub? Should platform specific stuff get moved up a level to std.darwin/std.freebsd/etc files?

That's a question I am intentionally deferring until the language is done. Probably there will be some boring answer such as, "we will delete all the libc declarations not used by the standard library before releasing 1.0".