This was misleading 'configure' into thinking we actually support AF_LINK,
but we're Linux, so we don't, and we never implemented the functions we
declared here either.
Reported to AOSP by Jun-ya Kato.
(cherry-pick of 5056f1fad1187cd67729bb04ba72397d78256f03.)
Change-Id: Ic67f674d2221497c8166994812bb5fc7f0831066