Update iossim.gyp to use src/build/ios/mac_build.gypi.

The mac_build.gypi will build the iossim executable using ninja.

BUG=None


Review URL: https://chromiumcodereview.appspot.com/10827200

git-svn-id: http://src.chromium.org/svn/trunk/src/build@152335 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -894,6 +894,11 @@
         'use_system_bzip2%': 1,
         'use_system_libxml%': 1,
         'use_system_sqlite%': 1,
+
+        # The Mac SDK is set for iOS builds and passed through to Mac
+        # sub-builds. This allows the Mac sub-build SDK in an iOS build to be
+        # overridden from the command line the same way it is for a Mac build.
+        'mac_sdk%': '<!(python <(DEPTH)/build/mac/find_sdk.py 10.6)',
       }],
       ['OS=="android"', {
         # Location of Android NDK.