* sysdeps/unix/sysv/linux/ifreq.h (__if_nextreq): New function.
* sysdeps/mach/hurd/ifreq.h (__if_nextreq): New function.
* sysdeps/gnu/ifaddrs.c (getifaddrs): Use __if_nextreq
for iterating through the list of interfaces.
* resolv/res_hconf.c (_res_hconf_reorder_addrs): Likewise.
* sysdeps/unix/grantpt.c (pts_name): Set errno when __ptsname_r fails.
Reported by Bruno Haible <bruno@clisp.org>.