Create the /images directory used by the resize functionality.

XenServer's resize uses /images as a known-path for each hypervisor.
This is a symlink to the storage repository so disks can be moved between
the /images path and the storage repository efficiently.

Change-Id: I13b39dbf5537ad45160c1af4cc10bd867b7f89c1
diff --git a/tools/xen/functions b/tools/xen/functions
index ebfd483..35c17d7 100644
--- a/tools/xen/functions
+++ b/tools/xen/functions
@@ -24,6 +24,16 @@
     fi
 }
 
+function create_directory_for_images {
+    if [ -d "/images" ]; then
+        echo "INFO: /images directory already exists, using that" >&2
+    else
+        local LOCALPATH="$(get_local_sr_path)/os-images"
+        mkdir -p $LOCALPATH
+        ln -s $LOCALPATH /images
+    fi
+}
+
 function extract_remote_zipball {
     local ZIPBALL_URL=$1