This patch adds prepends the 'SYSROOT' path specified by the environment
to the standard prefixes. By doing so we solve a whole bunch of problems
with cross-compiling and installing  python extensions.

The second part provides a fallback if the lib64 directory does not exist.
This is an ugly hack for now, the right fix would be to determine if the
target system is 32 or 64bit and adapt the libdir accordingly.

--- Lib/distutils/sysconfig.py	2008-09-27 15:55:24.000000000 +0200
+++ Lib/distutils/sysconfig.py.new	2008-09-27 15:55:36.000000000 +0200
@@ -19,9 +19,16 @@
 from distutils.errors import DistutilsPlatformError
 
 # These are needed in a couple of spots, so just compute them once.
+SYSROOT = os.getenv('SYSROOT')
 PREFIX = os.path.normpath(sys.prefix)
 EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
 
+# Make sure we respect the user specified SYSROOT environment variable
+# This is the first step to get distutils to crosscompile stuff
+if SYSROOT is not None:
+    PREFIX = os.path.normpath(SYSROOT+os.path.sep+PREFIX)
+    EXEC_PREFIX = os.path.normpath(SYSROOT+os.path.sep+EXEC_PREFIX)
+
 # python_build: (Boolean) if true, we're either building Python or
 # building an extension with an un-installed Python, so we use
 # different (hard-wired) directories.
@@ -94,6 +101,10 @@
 
     If 'prefix' is supplied, use it instead of sys.prefix or
     sys.exec_prefix -- i.e., ignore 'plat_specific'.
+
+    For the posix system we can not always assume to have a lib64 directory
+    e.g. for cross-compile between 32 & 64 bit systems. So we test if the
+    'lib64' directory exists and use the normal 'lib' dir as fallback.
     """
     if prefix is None:
         prefix = plat_specific and EXEC_PREFIX or PREFIX
@@ -102,6 +113,12 @@
         libpython = os.path.join(prefix,
                                  "@@GENTOO_LIBDIR@@", 
                                  "python" + get_python_version())
+
+        if not os.path.exists(libpython):
+            libpython = os.path.join(prefix,
+                                     "lib", 
+                                     "python" + get_python_version())
+        
         if standard_lib:
             return libpython
         else: