Persistence: Remove template specialization for time_t
Persistence: Remove template specialization for time_t

It does not appear to be necessary, and it can conflict with other
partial specializations.

Change-Id: Ia51d967d8610ac62a9c6ebe28847589c8eb77304
Fixes: QBS-1395
Reviewed-by: Vadim Zhukov <738aad35b848386233ccb8a58e3114b61545ab72@gmail.com>
Reviewed-by: Christian Stenger <accbb51712d7b9c4fb108439d01e716148e5f9e6@qt.io>

qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs