gnucash maint: Fix unlocalized date in status bar.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/e31f4c3f (commit)
	from  https://github.com/Gnucash/gnucash/commit/72ef48cb (commit)



commit e31f4c3f95f12871f8633843cf5cffe53196830d
Author: John Ralls <jralls at ceridwen.us>
Date:   Sat Jan 19 13:41:17 2019 -0800

    Fix unlocalized date in status bar.
    
    It seems that std::locales created by boost::locale::generator are
    not entirely compatible: If used to create a new locale with a facet
    for boost::date_time one ends up with the C locale and the facet.
    
    For the time being avoid the problem by using boost::locale to format
    dates and times. std::chrono gets calendar functions in C++20 so we
    can switch date-time backends once we can adopt it.



Summary of changes:
 libgnucash/engine/gnc-datetime.cpp            | 30 ++++++++-------------------
 libgnucash/engine/test/gtest-gnc-datetime.cpp |  2 +-
 2 files changed, 10 insertions(+), 22 deletions(-)