[PATCH v2][BZ 16852] Do not clobber recvmmsg argument.

[David Miller]

From: Ondřej Bílka <neleai@seznam.cz>
Date: Mon, 28 Apr 2014 18:04:20 +0200

> 	* sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Do not clobber
> 	timeout argument.

It is extremely unfortunate if we've defined this argument as const,
now you are making it so that the user has no mechanism to get the
updated timeval other than to define their own syscall stubs.

This is doubly unfortunately since there is absolutely no reason for
us to have defined the interface different from what the kernel
actually provides.