This is a small, simplistic utility that can be used to fetch and copy over a standard set of libc headers
as described here on macOS. The intention for this utility is to use it to update the libc headers shipped
with Zig, and used when cross-compiling to macOS (see this article for an amazing description of the zig cc
C compiler frontend).
Building is straightforward, although I should point out, with the current limitations of the lld linker, you should build the project natively on macOS
zig build
Running the generated binary fetch_them_macos_headers will create a new dir x86_64-macos-gnu with all
libc headers copied over
zig-cache/bin/fetch_them_macos_headers [cflags]
Currently there are no known cflags needed.