syscalls: Override detection of direct socket syscalls on i386, m68k, s390

syscalls: Override detection of direct socket syscalls on i386, m68k, s390

Bug-Debian: https://bugs.debian.org/809423
Forwarded: http://www.zytor.com/pipermail/klibc/2016-January/003882.html

The direct socket syscalls are now implemented on i386, m68k and s390,
making socketcall() obsolete.  However we need to keep klibc/unstable
working with the last stable kernel version (3.16) so we shouldn't use
them yet.

Gbp-Pq: Name syscalls-override-detection-of-direct-socket-syscalls-on-i386-m68k-s390.patch