I'm trying to resolve this issue on:

2.6-releasemaint
trunk
3.1-releasemaint
py3k

first by resolving issues configure.in, but there are a TON of
AC_TRY_RUN's, which means that this code cannot be cross-compiled as-is
(25 on 2.x -- 27 on 3.x).

Is requiring the end-user to define the autoconf variables appropriately
to their platform when running configure (when provided an error message
telling them so), a longterm sustainable requirement? I know it isn't as
user friendly, but this is a definite problem that either needs to be
fixed in the autoconf tests (if possible) or the C code itself.

I wouldn't mind updating the INSTALL or README files to reflect this
change either, if needed.