Bug 339853 arm64 times syscall unknown.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14616 a5019735-40e9-0310-863c-91ae7b9d1cf9
Bug 339855 arm64 unhandled getsid/setsid syscalls.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14617 a5019735-40e9-0310-863c-91ae7b9d1cf9