qemu-io: Add sigraise command

abort() has the sometimes undesirable side-effect of generating a core
dump. If that is not needed, SIGKILL has the same effect of abruptly
crash qemu; without a core dump.

Thus, -c abort is not always useful to simulate a qemu-io crash;
therefore, this patch adds a new sigraise command which allows raising
a signal.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1418032092-16813-2-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
