The qlocalexml.py Locale.C() had to replicate a whole lot of data that
isn't really relevant to how C differs from en_US and every addition
to what we support required further additions to it. So pass the en_US
Locale object to the pseudoconstructor so that C can inherit from it
and only override the parts where we care about the difference.
Hand-code shortening for short Jalali month names, to match Soroush's
original contribution, and include the narrow forms in the hard-coded
data to keep the generated data unchanged (for now). Note some of the
departures from CLDR; we may want to drop these overrides later.
In the process, convert the mapping from keys to locales to
consistently use IDs for all members of the key, instead of using the
(empty) code value for (as yet unused) variant; it now gets ID 0 and
is consistent with returns from codesToIdNames(). This makes life
easier for the code that now has to construct an en_US key.
Task-number: QTBUG-115158
Change-Id: I3d7acb6a4059daec1bba341fcf015c39c7a6803b
Reviewed-by: Kai Köhne <kai.koehne@qt.io>