> Martin meaning of target and host is different.
> There is no reason to use "Canadian Cross": build->host->target.
> It is about more simple cross-compilation case: build->host.

Terminology issues aside, I hope people still will understand my
objection. I meant it this way:
- host system: system hosting Python build process
- target system: system intended to run resulting Python executable
Whether that conforms to autoconf should be irrelevant, as long
as we aren't talking about configure.in changes.

> About loading of modules in build environment: some OS-es can run
> binaries from other OS-es.

Sure. However, I don't think this is the general case for
cross-compilation, and I don't think cross-compilation support in
Python should assume this is possible. Instead, cross-compilation
should assume that build system and target system have anything
in common (except that target headers and for-target cross tools
are installed on the build system).