QTimeZone - Add Mac backend

Add Mac backend support

Change-Id: Iafa2dbd925e18431f571e3eac62983015f8bc977
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QTimeZone - Add Windows backend

Add backend implementation for Windows times zones.

Change-Id: I30946f6672488c3f1d1d05754e9479aa62cce46f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QDateTime - Add QTimeZone support

Add support to QDateTime for time zones using the new QTimeZone class.

[ChangeLog][QtCore][QDateTime] Add support for a new Qt::TimeZone
spec to be used with QTimeZone to define times in a specific
time zone.

Change-Id: I21bfa52a8ba8989b55bb74e025d1f2b2b623b2a7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QDateTime - Remove some benchmark tests

Remove benchmark tests that are no longer required as they are simple
overloads of other methods.

Change-Id: I610211543d17c077f482fa2145ac3da7d0767282
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>