Qt Location has a soft dependency on qtjsondb.

Declare a new soft dependency on qtsystems.  This dependency is
dependent on whether location shifting support for China is
enabled.  By default it is not.

Change-Id: Id41451adb14e3c6cee0728ff343be85399fc4ac5
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>