Issue #290 Workaround for recognition of 64-bit system due to wrong CMAKE_SYSTEM_PROCESSOR value.

See also: http://www.cmake.org/pipermail/cmake/2013-February/053665.html
Issue #290 Fix post-build step for MCC targets on Mac OS.
Issue #290 Fix build/installation of MCC targets on Mac OS X.
Merge branch 'refs/heads/hotfix/#290-fix-mex-and-mcc-build' into release-3.0
Remove obsolete comment.