Use parameters in os_stack update (#3560)

This change makes os_stack module idempotent. Otherwise, re-use of the
module fails with:
Error updating stack: ERROR: The Parameter (...) was not provided.

Fixes #3165.

lib/ansible/modules/extras/cloud/openstack/os_stack.py

@@ -180,7 +180,8 @@ def _update_stack(module, stack, cloud):
             environment_files=module.params['environment'],
             timeout=module.params['timeout'],
             rollback=module.params['rollback'],
-            wait=module.params['wait'])
+            wait=module.params['wait'],
+            **module.params['parameters'])
 
         if stack['stack_status'] == 'UPDATE_COMPLETE':
             return stack