Debugger/Perspectives: Go back to QPointer<QObject>

Lifetime of the pointed-to object may end before that of
the plugin, so unique_ptr is the wrong choice.

This amends 01f2b982a2.

Change-Id: I76b9ac78348d2ae1e7eff0693b091dbe8475ab93
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/clangtools/clangtool.cpp

@@ -98,7 +98,10 @@ ClangTool::ClangTool(const QString &name)
     m_stopAction = Debugger::createStopAction();
 }
 
-ClangTool::~ClangTool() = default;
+ClangTool::~ClangTool()
+{
+    delete m_diagnosticView;
+}
 
 FileInfos ClangTool::collectFileInfos(Project *project, bool askUserForFileSelection) const
 {