Include compat.h in syscalls/msgsnd.c for MSG_COPY for older kernels.

This patch fixes this build error on Linux 3.7 and older.

  CC	syscalls/msgsnd.o
syscalls/msgsnd.c:19:40: error: ‘MSG_COPY’ undeclared here (not in a function)
make: *** [syscalls/msgsnd.o] Error 1

Signed-off-by: Vinson Lee <vlee@twitter.com>
idea to shorten runtime for hard to reproduce bugs
mount: define MS_NOSEC for older kernel

  CC	syscalls/mount.o
syscalls/mount.c:32: error: ‘MS_NOSEC’ undeclared here (not in a function)
make: *** [syscalls/mount.o] Error 1

Signed-off-by: Nikola Pajkovsky <npajkovs@redhat.com>