ladishd: don't create two vclients with same name

If the app first creates alsa (a2j) port, the created vclient is
not intrelinked because there is no jack client to interlink.
When the first jack port appears, because the jack client has
no interlinked client, a new vclient with same name was created.

This changeset implements a search by app uuid before new vclient
is created.

daemon/virtualizer.c

@@ -748,6 +748,9 @@ port_appeared(
       ASSERT(vclient != NULL);
     }
     else
+    {
+      vclient = ladish_graph_find_client_by_app(vgraph, app_uuid);
+      if (vclient == NULL)
       {
         log_info("creating new vclient");
         if (!ladish_client_create(NULL, &vclient))
@@ -771,6 +774,7 @@ port_appeared(
         }
       }
     }
+  }
 
   /********************/
   /* add newly appeared port to the virtual graph */