This patch fixes regressions provided by D14931.
Steps to reproduce (my system is neon/bionic with Qt 5.11.1 and KDevelop/master):
1) Start KDevelop and load some project
2) Start project build
3) Close KDevelop
4) Segfault happens
1) Incorrect signal processing. `OutputWidget::updateFilter()` slot is called from parent's destructor when `m_tabwidget`/`m_stackwidget` is deleted so we have destroyed `m_views` hash and segfault as a result.
2) Incorrect `QSharedPointer` usage. All handled objects have `QWidget` as a parent so we have double-free problem and and segfault as a result.