Fixed NB#295469: <coverity> defects for libmeegotouch/0.24.16-2_0m7/src/corelib/widgets/mcontainer.cpp
Fixed NB#295469: <coverity> defects for libmeegotouch/0.24.16-2_0m7/src/corelib/widgets/mcontainer.cpp

RevBy: Daniel d'Andrada
Details: Adds NULL check before dereferencing old central widget in
setCentralWidget() of MContainer. The current central widget could
be NULL.

https://meego.gitorious.org/meegotouch/libmeegotouch/merge_requests/2465

nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch,nemomobile-graveyard/libmeegotouch