Add SIOCATMARK ioctl support.

Patch from Austin English via BZ#335441.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14112 a5019735-40e9-0310-863c-91ae7b9d1cf9
Wire up recvmmsg on arm. BZ#334585.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14113 a5019735-40e9-0310-863c-91ae7b9d1cf9