commit 59324c8b09 added __socketcall
analogous to __syscall, returning the negated error rather than
setting errno. use it to simplify the fallback path of socket(),
avoiding extern calls and access to errno.
Author: Rich Felker <[email protected]>
Date: Tue Jul 30 17:51:16 2019 -0400
make __socketcall analogous to __syscall, error-returning