seccomp: add mbind() to the syscall whitelist

The "memory-backend-ram" QOM object utilizes the mbind(2) syscall to
set the policy for a memory range.  Add the syscall to the seccomp
sandbox whitelist.

Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>
Acked-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>
Tested-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

qemu-seccomp.c

@@ -235,7 +235,8 @@ static const struct QemuSeccompSyscall seccomp_whitelist[] = {
     { SCMP_SYS(fallocate), 240 },
     { SCMP_SYS(fadvise64), 240 },
     { SCMP_SYS(inotify_init1), 240 },
-    { SCMP_SYS(inotify_add_watch), 240 }
+    { SCMP_SYS(inotify_add_watch), 240 },
+    { SCMP_SYS(mbind), 240 }
 };
 
 int seccomp_start(void)