from `freeaddrinfo'.
`getifaddrs' and `freeifaddrs' are not in POSIX, they should not be
exposed along `freeaddrinfo' (through `__check_pf') which is POSIX.
* include/ifaddrs.h (__getifaddrs, __freeifaddrs): New declarations,
and use libc_hidden_def on them.
* inet/ifaddrs.c (__getifaddrs, __freeifaddrs): Use libc_hidden_def on
them.
* sysdeps/gnu/ifaddrs.c (__getifaddrs, __freeifaddrs): Likewise.
* inet/check_pf.c (__check_pf): Use __getifaddrs and __freeifaddrs
instead of getifaddrs and freeifaddrs.