gd_GB, hsb_DE, wa_BE: Add alternative month names (bug 23140).

gd_GB, hsb_DE, wa_BE: Add alternative month names (bug 23140).

As a followup of fixing bug 10871, these three languages now support two
grammatical cases of the month names.

This commit does not resolve the bug because there are more languages
to be committed.

	[BZ #23140]
	* localedata/locales/gd_GB (mon): Rename to...
	(alt_mon): This.
	(mon): Import from CLDR (genitive case).
	* localedata/locales/hsb_DE (mon): Rename to...
	(alt_mon): This.
	(mon): Import from CLDR (genitive case).
	* localedata/locales/wa_BE (mon): Rename to...
	(alt_mon): This.
	(mon): Add, fill with the proper genitive forms, but CLDR data
	is incomplete; completed according to the comments in this file.
	(d_t_fmt): Do not use "di" before the month name, no longer needed.

	* localedata/locales/wa_BE (country_name): Reword
	"Beljike" -> "Beldjike".