lib/locale.t: Make another test TODO if it fails

lib/locale.t: Make another test TODO if it fails

Many platforms have a few locales whose casing functionality is buggy.
However if only a few locales have failures, it probably means that Perl
is ok; and its the platform's locale definitions that are bad.  Earlier,
commit 6d5d702a337e9161f8eb85180a83c4469a8f7ed7 enhanced locale.t, if
only a few locales fail, to mark some tests which were showing these
kinds of bugs as TODOs.  This allowed robust tests to be added to
locale.t which previously were ommitted so as to not cause the tests to
fail if any locale on any platform was bad.  Not having these tests
allowed real Perl bugs to creep in.

This commit adds the /il match testing to the list of these tests.
Currently, it is set to hardly catch anything; and this allowed
another real bug to be introduced into Perl.

This commit was prompted by bugs in Darwin with ISO8859-4 and ISO8859-13
locales.