make gyp generate newer project files

patch from https://groups.google.com/forum/#!msg/gyp-developer/0JiSNtsKc30/xYxQFqRfrTcJ

deps/gyp/pylib/gyp/generator/xcode.py

@@ -604,7 +604,11 @@ def GenerateOutput(target_list, target_dicts, data, params):
 
     if parallel_builds:
       pbxp.SetProperty('attributes',
-                       {'BuildIndependentTargetsInParallel': 'YES'})
+                       {
+                           'BuildIndependentTargetsInParallel': 'YES',
+                           'LastUpgradeCheck': '0500'
+                       }
+                       )
     if project_version:
       xcp.project_file.SetXcodeVersion(project_version)
 

deps/gyp/pylib/gyp/xcodeproj_file.py

@@ -2158,6 +2158,7 @@ class XCTarget(XCRemoteObject):
         if configs.HasBuildSetting('PRODUCT_NAME') == 0:
           configs.SetBuildSetting('PRODUCT_NAME',
                                   self._properties['productName'])
+          configs.SetBuildSetting('COMBINE_HIDPI_IMAGES', 'YES')
 
   def AddDependency(self, other):
     pbxproject = self.PBXProjectAncestor()
@@ -2811,7 +2812,7 @@ class XCProjectFile(XCObject):
   _schema.update({
     'archiveVersion': [0, int,        0, 1, 1],
     'classes':        [0, dict,       0, 1, {}],
-    'objectVersion':  [0, int,        0, 1, 45],
+    'objectVersion':  [0, int,        0, 1, 46],
     'rootObject':     [0, PBXProject, 1, 1],
   })