Extensions should be installed to the targets libdir. This is important if e.g. host
has a 64bit /usr/lib64, but the target is 32bit and has $ROOT/usr/lib. Make sure we
respect the target's lib structure by getting the libdirname from Makefile.

--- Lib/distutils/command/install.py	2009-03-06 22:18:21.000000000 +0000
+++ Lib/distutils/command/install.py.new	2009-03-06 22:23:17.000000000 +0000
@@ -38,8 +38,8 @@
 
 INSTALL_SCHEMES = {
     'unix_prefix': {
-        'purelib': '$base/@@GENTOO_LIBDIR@@/python$py_version_short/site-packages',
-        'platlib': '$platbase/@@GENTOO_LIBDIR@@/python$py_version_short/site-packages',
+        'purelib': '$base/$libdirname/python$py_version_short/site-packages',
+        'platlib': '$platbase/$libdirname/python$py_version_short/site-packages',
         'headers': '$base/include/python$py_version_short/$dist_name',
         'scripts': '$base/bin',
         'data'   : '$base',
@@ -289,6 +289,7 @@
         # everything else.
         self.config_vars['base'] = self.install_base
         self.config_vars['platbase'] = self.install_platbase
+        self.config_vars['libdirname'] = self.install_libdirname
 
         if DEBUG:
             from pprint import pprint
@@ -394,6 +395,10 @@
 
             self.install_base = self.prefix
             self.install_platbase = self.exec_prefix
+            self.install_libdirname = get_config_vars('LIBDIRNAME')[0]
+            if self.install_libdirname is None:
+                self.install_libdirname = @@GENTOO_LIBDIR@@
+
             self.select_scheme("unix_prefix")
 
     # finalize_unix ()