Mojo interface libraries: set install name and search path properly on Mac.

This fixed the Mac non-component build.

BUG=346766
TEST=Mojo tests (non-component build) work on Mac
R=thakis@chromium.org, viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/188693006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255791 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255791