Make QtSensors use Q_DECL_OVERRIDE

This patch aims to make QtSensors uses Q_DECL_OVERRIDE uniformly across
the module

Task-number: QTBUG-27392
Change-Id: I5f814f93307159175f92e29a9990587c03cce96f
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>
Bump MODULE_VERSION to 5.2.1

Change-Id: I5082d09607f08c4daad72a8530f7f76feac397fa
Reviewed-by: Matti Paaso <matti.paaso@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Merge remote-tracking branch 'upstream/stable' into wip/tizen

Change-Id: Ie82cf5e0565de901e8bca85b01dca17c26982be2