Fix dependency broken on mac when building FAT binaries.

When trying to build shared_library or loadable_module, build.ninja
has a rule to depend on .dylib.TOC or .so.TOC.  However, WriteLink in
ninja.py forget to create the rule for .TOC for FAT binaries.
As a result, generated build.ninja won't has a rule for .TOC,
which cause build failure.

Note that I only fixed a part of the issue 411, which is needed for my goal.
I or somebody else need more work to make gyp in the issue 411 work
as epxected.

BUG=https://code.google.com/p/gyp/issues/detail?id=411
Review URL: https://codereview.chromium.org/629893002/

Patch from Yoshisato Yanagisawa <yyanagisawa@chromium.org>!


git-svn-id: http://gyp.googlecode.com/svn/trunk@2000 78cadc50-ecff-11dd-a971-7dbc132099af