Add support for running multiple n-cpus for performance testing

When using the fake VIRT_DRIVER, we can launch an arbitrary number of
instances, the next step for performance testing is running an arbitrary
number of n-cpus. This can be done with the following settings in your localrc

 VIRT_DRIVER=fake
 NUMBER_FAKE_NOVA_COMPUTE=50

This can be used for things like measuring load from n-cpu's periodic tasks.

Change-Id: I40e0f05374e2c10c48ea6b8816ef6e7609b3dc80
diff --git a/stackrc b/stackrc
index 36171cc..8d9c1f2 100644
--- a/stackrc
+++ b/stackrc
@@ -187,6 +187,9 @@
             LIBVIRT_GROUP=libvirtd
         fi
         ;;
+    fake)
+        NUMBER_FAKE_NOVA_COMPUTE=${NUMBER_FAKE_NOVA_COMPUTE:-1}
+        ;;
     xenserver)
         # Xen config common to nova and neutron
         XENAPI_USER=${XENAPI_USER:-"root"}