localedef: Add tests-container test for --no-hard-links.

The new tst-localedef-hardlinks verifies that when compiling
two locales (with default output directory) one with
--no-hard-links and one without the option, results in the
expected behaviour.  When --no-hard-links is used the link
counts on LC_CTYPE is 1, indicating that even thoug the two
locale are identical (though different named source files and
output direcotry) the localedef did not carry out the hard
link optimization.  Then when --no-hard-links is omitted the
localedef hard link optimization is correctly carried out and
for 2 compiled locales the link count for LC_CTYPE is 2.

Reviewed-by: DJ Delorie <dj@redhat.com>