Improve generated Makefile rules for rules with 2 outputs.

test/actions-multiple-outputs/src/multiple-outputs.gyp

 # Copyright (c) 2015 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
-      'target_name': 'depfile_target',
+      'target_name': 'multiple-outputs',
       'type': 'none',
       'actions': [
         {
-          'action_name': 'depfile_action',
-          'inputs': [
-            'input.txt',
+          'action_name': 'action1',
+          'inputs': [],
+          'outputs': [
+            '<(PRODUCT_DIR)/out1.txt',
+            '<(PRODUCT_DIR)/out2.txt',
           ],
-          'outputs': [
-            'output.txt',
-          ],
-          'depfile': 'depfile.d',
-          'action': [ ]
+          'action': ['python', 'touch.py', '<@(_outputs)'],
         },
       ],
     },
   ],
 }