Fixes: unit tests crash issue.
Fixes: unit tests crash issue.

RevBy: TrustMe
Details: Some unit tests are crashed. Because our unit tests are using
the stub MGConfItem, which depends on a MGConfItemStub object. If that
MGConfItemStub object is destroyed before some MGConfItem objects (e.g.
some static MGConfItem object declared by MLocale), then core dump will
happen. The fix is using a dynamic created MGConfItemStub object to avoid
crash.

KDE/plasma-maliit-plugins,develersrl/maliit-demo-qml,KDE/plasma-maliit-plugins,maliit/plugins,develersrl/maliit-demo-qml,RHawkeyed/plugins,RHawkeyed/plugins,RHawkeyed/plugins,maliit/plugins,RHawkeyed/plugins,RHawkeyed/plugins,develersrl/maliit-demo-qml,maliit/plugins,KDE/plasma-maliit-plugins,KDE/plasma-maliit-plugins,maliit/plugins,develersrl/maliit-demo-qml