dzl-date-time: Use the new "%OB" format
Due to the recent changes introduced in glibc 2.27 which hopefully will be followed by a similar change in glib
"%OB" is the correct format to obtain a month name as used in the calendar header (standalone, nominative case). The same rule has been working in BSD family (including OS X) since 1990s. Currently the function
dzl_g_date_time_format_for_display uses this line:
return g_date_time_format (self, "%B");
This will have to be replaced with
"%OB" and the minimum required version of glib must be bumped to 2.55.2.
Unfortunately, I'm afraid that glib bug 749206 must be fixed first.