macos 9 isn't supported

git-svn-id: http://svn.python.org/projects/python/trunk@68515 6015fed2-1504-0410-9fe1-9d1591cc4771

Author: benjamin.peterson

Doc/library/sys.rst

@@ -587,7 +587,6 @@ always available.
    Windows          ``'win32'``
    Windows/Cygwin   ``'cygwin'``
    Mac OS X         ``'darwin'``
-   Mac OS 9         ``'mac'``
    OS/2             ``'os2'``
    OS/2 EMX         ``'os2emx'``
    RiscOS           ``'riscos'``