bug 980725: multi_host is always set to True with virtdriver=xenserver

set MULTI_HOST according to the value as defined in localrc or other rc files.

Change-Id: Ifc5d0fff06bffd39ab4ff1c1a6fa5d4ab10b9e27
diff --git a/tools/xen/build_xva.sh b/tools/xen/build_xva.sh
index c235485..1b41963 100755
--- a/tools/xen/build_xva.sh
+++ b/tools/xen/build_xva.sh
@@ -177,7 +177,7 @@
 #!/bin/bash
 cd /opt/stack/devstack
 killall screen
-UPLOAD_LEGACY_TTY=yes HOST_IP=$PUB_IP VIRT_DRIVER=xenserver FORCE=yes MULTI_HOST=1 HOST_IP_IFACE=$HOST_IP_IFACE $STACKSH_PARAMS ./stack.sh
+UPLOAD_LEGACY_TTY=yes HOST_IP=$PUB_IP VIRT_DRIVER=xenserver FORCE=yes MULTI_HOST=$MULTI_HOST HOST_IP_IFACE=$HOST_IP_IFACE $STACKSH_PARAMS ./stack.sh
 EOF
 chmod 755 $STAGING_DIR/opt/stack/run.sh