Xcode: Add xcdatamodeld = wrapper.xcdatamodeld in extension_map 

.xcdatamodeld documents are used for Model File Format. 
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmModelFormat.html 

Note that .xcdatamodel has already been supported since gyp r1529. 

BUG=303

Patch from Roberto Cosenza <robcos@google.com>
via Yohei Yukawa <yukawa@chromium.org>

Review URL: https://codereview.chromium.org/351223002/


git-svn-id: http://gyp.googlecode.com/svn/trunk@1948 78cadc50-ecff-11dd-a971-7dbc132099af
diff --git a/pylib/gyp/xcodeproj_file.py b/pylib/gyp/xcodeproj_file.py
index 79c3abc..13eaf3a 100644
--- a/pylib/gyp/xcodeproj_file.py
+++ b/pylib/gyp/xcodeproj_file.py
@@ -1512,6 +1512,7 @@
         'xcassets':    'folder.assetcatalog',
         'xcconfig':    'text.xcconfig',
         'xcdatamodel': 'wrapper.xcdatamodel',
+        'xcdatamodeld':'wrapper.xcdatamodeld',
         'xib':         'file.xib',
         'y':           'sourcecode.yacc',
       }