removed sys.platform == 'mac' support in distutils.dist.parse_command_line and improved test coverage

distutils.test_build_clib added a new line at the end of the file, to avoid a warning with some compilers

Fixed Issue 5900: distutils.command.build_ext - Ensure RUNPATH is added to extension modules with RPATH if GNU ld is used

Update bdist_msi so that the generated MSIs for pure Python modules can install to any version of Python, like the generated EXEs from bdist_wininst. (Previously, you had to create a new MSI for each version of Python.)