To be used in conjunction with the --template argument to git-clone.

The hooks all redirect to build/git-hooks, which are files under
revision control.  This allows us to version the hooks along with
the source code.

TBR=mmoss@chromium.org,cmp@chromium.org
Review URL: https://codereview.chromium.org/11689005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@174738 0039d316-1c4b-4281-b951-d872f2087c98