Create mechanism for enabling placement-client on subnodes

When doing multinode devstack we need a way to specify that we've
enabled for the placement service. We use a pseudo service of
placement-client for this.

Change-Id: I04a655fbc58913b3d607400a7f677be299499142
diff --git a/stack.sh b/stack.sh
index f4bac30..1817f61 100755
--- a/stack.sh
+++ b/stack.sh
@@ -869,6 +869,16 @@
     configure_placement
 fi
 
+# create a placement-client fake service to know we need to configure
+# placement connectivity. We configure the placement service for nova
+# if placement-api or placement-client is active, and n-cpu on the
+# same box.
+if is_service_enabled placement placement-client; then
+    if is_service_enabled n-cpu; then
+        configure_placement_nova_compute
+    fi
+fi
+
 if is_service_enabled horizon; then
     # django openstack_auth
     install_django_openstack_auth