Prepare to support taking CLDR data from its github upstream

We've previously used the zip-file form, but that's not been published
for CLDR v44.1 - the advice on the list was to use github
instead. That, however, has ↑↑↑ as a special value for fields, meaning
to inherit from a prent locale. So special-case that value. I have
verified that v44 from the zip file produces identical results to v44
from github, with this minor fix. As it happens v44.1 also produces
identical results.

Pick-to: 6.5
Change-Id: I6eb0aedda7556753cdc83bb9d76652fbb68dc669
Reviewed-by: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
(cherry picked from commit bcdd51cfae24731a73d008add23d3c1e85bbd8d0)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit c112981789f5885e5db0daa4a081fa26708bafb0)

util/locale_database/cldr2qlocalexml.py

@@ -3,16 +3,21 @@
 # SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 """Convert CLDR data to QLocaleXML
 
-The CLDR data can be downloaded from CLDR_, which has a sub-directory
+The CLDR data can be downloaded as a zip-file from CLDR_, which has a
-for each version; you need the ``core.zip`` file for your version of
+sub-directory for each version; you need the ``core.zip`` file for
-choice (typically the latest). This script has had updates to cope up
+your version of choice (typically the latest), which you should then
-to v38.1; for later versions, we may need adaptations. Unpack the
+unpack. Alternatively, you can clone the git repo from github_, which
-downloaded ``core.zip`` and check it has a common/main/ sub-directory:
+has a tag for each release and a maint/maint-$ver branch for each
-pass the path of that root of the download to this script as its first
+major version. Either way, the CLDR top-level directory should have a
-command-line argument. Pass the name of the file in which to write
+subdirectory called common/ which contains (among other things)
-output as the second argument; either omit it or use '-' to select the
+subdirectories main/ and supplemental/.
-standard output. This file is the input needed by
+
-``./qlocalexml2cpp.py``
+This script has had updates to cope up to v44.1; for later versions,
+we may need adaptations. Pass the path of the CLDR top-level directory
+to this script as its first command-line argument. Pass the name of
+the file in which to write output as the second argument; either omit
+it or use '-' to select the standard output. This file is the input
+needed by ``./qlocalexml2cpp.py``
 
 When you update the CLDR data, be sure to also update
 src/corelib/text/qt_attribution.json's entry for unicode-cldr. Check
@@ -28,6 +33,7 @@ time zone names; see cldr2qtimezone.py for details.
 All the scripts mentioned support --help to tell you how to use them.
 
 .. _CLDR: https://unicode.org/Public/cldr/
+.. _github: https://github.com/unicode-org/cldr
 """
 
 from pathlib import Path

util/locale_database/ldml.py

@@ -204,7 +204,10 @@ class LocaleScanner (object):
             for elt in self.__find(xpath):
                 try:
                     if draft is None or elt.draft <= draft:
-                        return elt.dom.firstChild.nodeValue
+                        value = elt.dom.firstChild.nodeValue
+                        # The github version of CLDR uses '↑↑↑' to indicate "inherit"
+                        if value != '↑↑↑':
+                            return value
                 except (AttributeError, KeyError):
                     pass
         except Error as e: