at this again, when porting SUSE patches to 3.6.0 :) ( :( )

Last time there was a discussion, Barry suggested using sysconfig variables to find the proper libdir. Trouble is, to fill out the variables, sysconfig itself uses two sources:
a) compiled-in information from the binary, and
b) Makefile items
Makefile seems an obvious location for storing the libdir info, except, well, to FIND the makefile in the first place, we are using sysconfig variables.... you see where this is heading.

So, given that sysconfig is the correct Primary Source for libdir info, we have three options to get it there:
1. compile it into the binary. sys.implementation.platlibdir seems as good as any -- i'm not completely convinced that this is a property of the _implementation_, but, well.
2. modify sysconfig.py at build time
3. guess it from the environment

And options (2) and (3) seem wrong, so i'm going with (1) for now