Build atom-shell with ninja.

common.gypi

@@ -0,0 +1,42 @@
+{
+  'variables': {
+    'clang': 0,
+    'source_root': '<!(python tools/mac/source_root.py)',
+    'conditions': [
+      ['OS=="mac"', {
+        'clang': 1,
+        'mac_sdk%': '<!(python tools/mac/find_sdk.py 10.8)',
+      }],
+    ],
+  },
+  'conditions': [
+    ['clang==1', {
+      'make_global_settings': [
+        ['CC', '/usr/bin/clang'],
+        ['CXX', '/usr/bin/clang++'],
+        ['LINK', '$(CXX)'],
+        ['CC.host', '$(CC)'],
+        ['CXX.host', '$(CXX)'],
+        ['LINK.host', '$(LINK)'],
+      ],
+      'target_defaults': {
+        'cflags_cc': [
+          '-std=c++11',
+        ],
+        'xcode_settings': {
+          'CC': '/usr/bin/clang',
+          'LDPLUSPLUS': '/usr/bin/clang++',
+          'OTHER_CPLUSPLUSFLAGS': [
+            '$(inherited)', '-std=gnu++11'
+          ],
+          'OTHER_CFLAGS': [
+            '-fcolor-diagnostics',
+          ],
+
+          'SDKROOT': 'macosx<(mac_sdk)',     # -isysroot
+          'GCC_C_LANGUAGE_STANDARD': 'c99',  # -std=c99
+        },
+      },
+    }],  # clang==1
+  ],
+}