lv_LV locale: fix collation [BZ #15537]

	[BZ #15537]
	* localedata/locales/lv_LV (LC_COLLATE): Fix collation by
	using “copy "iso14651_t1"” and then implementing the
	collation rules for lv from CLDR on top of that.
	* Makefile: Add lv_LV.UTF-8 to test-input and to the list
	of locales to be built for testing.
	* lv_LV.UTF-8.in: New file with test data to test the Latvian
	sorting.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>