This change integrates e58abc1110b335a3341e8ad5821ad8e3880d9bb2 from
https://github.com/ahgamut/musl-cross-make/ which fixes the issues we
were having with our C language extension for symbolic constants. This
change also performs some code cleanup and bug fixes to getaddrinfo().
It's now possible to compile projects like ncurses, readline and python
without needing to patch anything upstream, except maybe a line or two.
Pretty soon it should be possible to build a Linux distro on Cosmo.
This change improves copy_file_range(), sendfile(), splice(), openpty(),
closefrom(), close_range(), fadvise() and posix_fadvise() in addition to
writing tests that confirm things like errno and seeking behavior across
platforms. We now less aggressively polyfill behavior with some of these
functions when the platform support isn't available. Please see:
https://justine.lol/cosmopolitan/functions.html
Justine says nay for the time being. Only XNU implements this. It's not
clear what ABI XNU is using but it's obviously not the one in the POSIX
documentation link below. Since all platforms implement vfork, it might
be better to empirically gauge the intersection of consensus which will
have better performance than this interface.
https://pubs.opengroup.org/onlinepubs/009696699/xrat/xsh_chap03.html
