make MarbleMapPrivate::m_geometryLayer a value
make MarbleMapPrivate::m_geometryLayer a value

* resolves a memory leak

oberluz/marble,Earthwings/marble,AndreiDuma/marble,AndreiDuma/marble,Earthwings/marble,David-Gil/marble-dev,tucnak/marble,adraghici/marble,quannt24/marble,quannt24/marble,rku/marble,utkuaydin/marble,Earthwings/marble,rku/marble,tucnak/marble,tucnak/marble,tzapzoor/marble,rku/marble,Earthwings/marble,oberluz/marble,adraghici/marble,David-Gil/marble-dev,David-Gil/marble-dev,tzapzoor/marble,probonopd/marble,tucnak/marble,quannt24/marble,adraghici/marble,probonopd/marble,rku/marble,AndreiDuma/marble,Earthwings/marble,David-Gil/marble-dev,utkuaydin/marble,tucnak/marble,AndreiDuma/marble,utkuaydin/marble,quannt24/marble,probonopd/marble,utkuaydin/marble,adraghici/marble,tzapzoor/marble,tucnak/marble,quannt24/marble,oberluz/marble,quannt24/marble,tzapzoor/marble,probonopd/marble,oberluz/marble,oberluz/marble,tzapzoor/marble,rku/marble,quannt24/marble,oberluz/marble,Earthwings/marble,utkuaydin/marble,probonopd/marble,utkuaydin/marble,David-Gil/marble-dev,rku/marble,AndreiDuma/marble,adraghici/marble,tzapzoor/marble,tzapzoor/marble,tzapzoor/marble,David-Gil/marble-dev,probonopd/marble,adraghici/marble,AndreiDuma/marble,tucnak/marble,probonopd/marble