multi-platform, multi-locale regression tests

I'm looking for some ideas on how to deal with the regression tests for
the per-column collation feature. These are the issues:

* The feature only works on some platforms (tentatively: Linux,
Windows).

-> Possible solution: like xml test

* The locale names are platform dependent, so there would need to be
different test files per locale.

* The test files need to use some non-ASCII characters. So far, I have
encoded the test file in UTF-8 and run the tests with make check
MULTIBYTE=UTF8.

* Also, the allowed collations depend on the server encoding, so any
solution for the previous point that results in the server encoding of
the test database being variable will make the setup of the regression
test SQL file more interesting.

* Of course the actual sort orders could also be different on different
platforms, but that problem can likely be contained.

One possible way out is not to include these tests in the main test set
and instead require manual invocation.

Better ideas?