arm64-linux: make restarting of syscalls interrupted by signals work


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13823 a5019735-40e9-0310-863c-91ae7b9d1cf9
Enable sys_ppoll, sys_kill, sys_socketpair.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13824 a5019735-40e9-0310-863c-91ae7b9d1cf9