nwfilter: Fix return value comparison for virNWFilterTriggerVMFilterRebuild

Should compare < 0 to be correct.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/conf/virnwfilterobj.c

@@ -253,7 +253,7 @@ virNWFilterObjTestUnassignDef(virNWFilterObjPtr obj)
 
     obj->wantRemoved = true;
     /* trigger the update on VMs referencing the filter */
-    if (virNWFilterTriggerVMFilterRebuild())
+    if (virNWFilterTriggerVMFilterRebuild() < 0)
         rc = -1;
 
     obj->wantRemoved = false;
@@ -345,7 +345,7 @@ virNWFilterObjListAssignDef(virNWFilterObjListPtr nwfilters,
 
         obj->newDef = def;
         /* trigger the update on VMs referencing the filter */
-        if (virNWFilterTriggerVMFilterRebuild()) {
+        if (virNWFilterTriggerVMFilterRebuild() < 0) {
             obj->newDef = NULL;
             virNWFilterObjUnlock(obj);
             return NULL;