Free most APIs using QTimeZone from feature timezone and route all
APIs taking a naked QTimeSpec via these, in preparation for their
eventual deprecation. Since qtimezone.h includes qdatetime.h (and MSVC
blocks our ability to remove the need for that), qdatetime.h's
declarations can't use a default value for QTimeZone parameters; so
add overloads taking no zone (or spec) to handle that.
[ChangeLog][QtCore][QDateTime] All QDateTime APIs involving a
Qt::TimeSpec can now be routed via QTimeZone's lightweight time
description support, saving the need to have different code paths for
different time specs. In the process, QDateTime gains a
timeRepresentation() method to return a QTimeZone reporting the
(possibly lightweight) time description it uses. (The older timeZone()
method always returns a non-lightweight QTimeZone, whose timeSpec() is
Qt::TimeZone.)
Task-number: QTBUG-108199
Change-Id: I23e43401eb2dbe9b7b534ca6401389920dd96b3c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
f46c18c627