Backport compute availabilityzones extension from the upstream

Change-Id: I2b824285af94669e1e57f61e4787b398e0db94d0
Related-PROD: PROD-34531
diff --git a/openstack/compute/v2/extensions/availabilityzones/urls.go b/openstack/compute/v2/extensions/availabilityzones/urls.go
new file mode 100644
index 0000000..9d99ec7
--- /dev/null
+++ b/openstack/compute/v2/extensions/availabilityzones/urls.go
@@ -0,0 +1,11 @@
+package availabilityzones
+
+import "github.com/gophercloud/gophercloud"
+
+func listURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL("os-availability-zone")
+}
+
+func listDetailURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL("os-availability-zone", "detail")
+}