QTimeZone - Define new class and api

Implement the new QTimeZone class based on the Olsen Time Zone ID's.

This is the base implementation and does not include the Platform
backends which are implemented separately.

This change does include a default UTC backed to be used if no Platform
backend is available, i.e. if QT_NO_SYSTEMLOCALE is set and ICU is not
configured.  This backend also provides a default set of time zones in
the standard "UTC+00:00" offset format that are guaranteed to always
exist regardless of the Platform backend.

This change includes conversion functions between the Olsen ID's and
Windows ID's using a conversion table based on Unicode CLDR data.
This is implemented for all platforms for scenarios such as a Linux
program needing to communicate with a Windows Exchange Server using
the Windows ID.

The CLDR conversion table is included under the UNICODE license, see
http://unicode.org/copyright.html for details.

[ChangeLog][QtCore][QTimeZone] Added new QTimeZone class to support
time tone calculations using the host platform time zone database
and the Olsen time zone ID's.

Change-Id: Ibb417d08cf2663a0979d2be855d2c6ad6ad01509
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QTimeZone - Add ICU support

Add ICU backend for QTimeZone

Change-Id: I92e53a848477e366591102064b093e936f0b49d2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QTimeZone - Add TZ File Backend

Add a backend for TZ Files.

If available uses ICU for the display names and  translations, otherwise
the abbreviation is used.

Change-Id: I58c777462810b1a76ea7bd95886836b70b8a3db5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>