Log Message:
Internally, Python has a set of modules depending on "platform".  The
"platform" in Python terms is different for Linux kernel 2.* Vs Linux
kernel 3.*.  Add in support to pull in a different PLIST for Linux 3.*.

Fixes build under Ubuntu 11.10.

XXX Perhaps it would be cleaner to name the PLIST to match the python platform
name - since we already calculate that anyway, and that is exactly what drives
the contents of these PLISTs.