virsh migrate: Properly check for --parallel-connections

Ever since --parallel-connections option for virsh migrate was
introduced we did not properly check the return value of
vshCommandOptInt. We would set VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS
parameter even if vshCommandOptInt returned 0 (which means
--parallel-connections was not specified) when another int option which
was checked earlier was specified with a nonzero value.

Specifically, running virsh migrate with either
--auto-converge-increment, --auto-converge-initial, --comp-mt-dthreads,
--comp-mt-threads, or --comp-mt-level would set
VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS parameter and if --parallel
option was not used, libvirt would complain

    error: invalid argument: Turn parallel migration on to tune it

even though --parallel-connections option was not used at all.

https://bugzilla.redhat.com/show_bug.cgi?id=1726643Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

tools/virsh-domain.c

@@ -10785,13 +10785,14 @@ doMigrate(void *opaque)
             goto save_error;
     }
 
-    if (vshCommandOptInt(ctl, cmd, "parallel-connections", &intOpt) < 0)
+    if ((rv = vshCommandOptInt(ctl, cmd, "parallel-connections", &intOpt)) < 0) {
         goto out;
-    if (intOpt &&
-        virTypedParamsAddInt(&params, &nparams, &maxparams,
-                             VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS,
-                             intOpt) < 0)
-        goto save_error;
+    } else if (rv > 0) {
+        if (virTypedParamsAddInt(&params, &nparams, &maxparams,
+                                 VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS,
+                                 intOpt) < 0)
+            goto save_error;
+    }
 
     if (vshCommandOptBool(cmd, "live"))
         flags |= VIR_MIGRATE_LIVE;