bdiff.c: Added support for py3k.
This patch adds support for py3k in bdiff.c. This is accomplished by including
a header file responsible for abstracting the API differences between python 2
and python 3.
% prepare repo
adding a
% import patch
applying patch from stdin
patching file a
Hunk #1 succeeded at 43 (offset 34 lines).
Hunk #2 succeeded at 87 (offset 34 lines).
Hunk #3 succeeded at 109 (offset 34 lines).
a
% compare imported changes against reference file