MFC r302920

Add a regression test to make sure the Russian collation is actually working

when importing collation support from Dragonfly/Illumos amdmi3@ tested the
collation branch and reported an issue with Russian collation. John Marino fixed
the issue in Dragonfly and I merged it back to FreeBSD.

Now that Illumos is working on merging our fixes they (Lauri Tirkkonen) found
issues with the commit that fixes the russian collation in UTF-8 that resulted
in a crash with strxfrm(3) and the ISO-8859-5 locale (fixed in FreeBSD r302916).
This small test was written to ensure we do not bring back the old issue with
russian collation while fixing the other issue.