lib/locale.t: Add tests, fix test names

lib/locale.t: Add tests, fix test names

It is unfortunate that tests are in two places in this file.  The reason
is to avoid doing eval's (to avoid any perturbations that might cause)
but be under the scope of two different locale forms.  This adds text to
remind maintainers that they should create copies when adding tests, and
includes the new tests that have previously been added to one place but
not the other, and includes the new improved test names.