The British people apparently use am/pm in time, so make it available to
them.  While we're here, sync the date_fmt field from en_GB to cy_GB.

Fedora has been carrying this for the better part of a decade, and Debian
has had it, and now that I've gotten a request from some British people
to add it to Gentoo, I'd rather get it merged into mainline.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2012-04-12  Mike Frysinger  <vapier@gentoo.org>

	[BZ #3768]
	* locales/en_GB: Set am_pm and t_fmt_ampm fields.
	* locales/cy_GB: Likewise.  Also copy date_fmt from en_GB.