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

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index c8a521dab0a8b98e1d458d3c30b080d9cefd4ee7..41333d2375d59b4a3fbb0670c8377f5c5433f559 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -893,6 +893,10 @@
         'use_system_bzip2%': 1,
         'use_system_libxml%': 1,
         'use_system_sqlite%': 1,
+
+        # Use a variable for the mac sdk, so that overriding this variable
+        # allows specifying the sdk that will be used for mac sub-builds.

[stuartmorgan, 2012/08/20 07:29:53]

Let's make this a bit clearer. How about:

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.

[lliabraa, 2012/08/20 13:47:42]

Done.

+        'mac_sdk%': '<!(python <(DEPTH)/build/mac/find_sdk.py 10.6)',
       }],
       ['OS=="android"', {
         # Location of Android NDK.