Fixed 2 Coverity reported issues.
Fixed 2 Coverity reported issues.

CID 11681: Uninitialized scalar field (UNINIT_CTOR)
Non-static class member _previousHeight is not initialized in this constructor nor in any functions that it calls.
Non-static class member _previousWidth is not initialized in this constructor nor in any functions that it calls.

CID 11688: Uninitialized scalar field (UNINIT_CTOR)
Non-static class member _previousHeight is not initialized in this constructor nor in any functions that it calls.
Non-static class member _previousWidth is not initialized in this constructor nor in any functions that it calls.



artoolkit/osg,scrawl/osg,marchelbling/osg,openscenegraph/osg,jtorresfabra/osg,scrawl/osg,marchelbling/osg,jtorresfabra/osg,scrawl/osg,openscenegraph/osg,tomasthoresen/osg,artoolkit/osg,openscenegraph/osg,scrawl/osg,marchelbling/osg,marchelbling/osg,tomasthoresen/osg,jtorresfabra/osg,tomasthoresen/osg,tomasthoresen/osg,artoolkit/osg,jtorresfabra/osg,openscenegraph/osg,artoolkit/osg