Always constructing the en-US CalendarWrapper defeats the original intention
that not for every construction of SvNumberFormatter a calendar is needed, plus
if no en-US is requested constructing such calendar is just wasted.

Since

	commit 2a226965
	Date:   Mon Jul 10 15:56:32 2017 +0200

		tdf#109045: store en calendar separately in OnDemandCalendarWrapper

Change-Id: I06e13754f03fc1fe4fbf48b76ccb82c917606480