Change setupext.py to be compatible with Mac OS X (darwin);

include instructions for users of packaging systems (e.g. MacPorts).

Author: r-owen

setupext.py

@@ -58,15 +58,13 @@
     'linux3' : ['/usr/local', '/usr'],
     'linux'  : ['/usr/local', '/usr',],
     'cygwin' : ['/usr/local', '/usr',],
-    '_darwin' : ['/sw/lib/freetype2', '/sw/lib/freetype219', '/usr/local',
-                '/usr', '/sw'],
-    # it appears builds with darwin are broken because of all the
-    # different flags the deps can be compile with, so I am pushing
-    # people to :
-    #   make -f make.osx fetch deps mpl_build mpl_install
-
-    'darwin' : [],
+    
+    # darwin is Mac OS X.
+    # The default configuration works for Apple's built-in python, python.org python and Homebrew python
+    # If you use Fink python then prepend '/sw'
+    # If you use MacPorts python then prepend '/opt/local'
 
+    'darwin' : ['/usr/local/', '/usr', '/usr/X11'],
     'freebsd4' : ['/usr/local', '/usr'],
     'freebsd5' : ['/usr/local', '/usr'],
     'freebsd6' : ['/usr/local', '/usr'],