seccomp: add semctl() to the syscall whitelist

QEMU needs to call semctl() for correct operation.  This particular
problem was identified on shutdown with the following commandline:

 # qemu -sandbox on -monitor stdio \
   -device intel-hda -device hda-duplex -vnc :0
Signed-off-by: NPaul Moore <pmoore@redhat.com>
Signed-off-by: NEduardo Otubo <eduardo.otubo@profitbricks.com>

qemu-seccomp.c

@@ -230,7 +230,8 @@ static const struct QemuSeccompSyscall seccomp_whitelist[] = {
     { SCMP_SYS(timerfd_create), 240 },
     { SCMP_SYS(shmctl), 240 },
     { SCMP_SYS(mlock), 240 },
-    { SCMP_SYS(munlock), 240 }
+    { SCMP_SYS(munlock), 240 },
+    { SCMP_SYS(semctl), 240 }
 };
 
 int seccomp_start(void)