Debugger: Consolidate icon storage handling

We settled now on global objects being fine for the purpose
in Core and ProjectExplorer, so there's no point in using
something more fancy in the debugger.

Change-Id: I72e45f398c09d22894419c274dfbea77da0fc153
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/debuggerplugin.cpp

@@ -998,8 +998,6 @@ public:
 
     QToolButton *m_reverseToolButton = 0;
 
-    QIcon m_locationMarkIcon;
-
     QLabel *m_threadLabel = 0;
     QComboBox *m_threadBox = 0;
 
@@ -1310,8 +1308,6 @@ bool DebuggerPluginPrivate::initialize(const QStringList &arguments,
     const Context cppDebuggercontext(C_CPPDEBUGGER);
     const Context cppeditorcontext(CppEditor::Constants::CPPEDITOR_ID);
 
-    m_locationMarkIcon = Icons::LOCATION.icon();
-
     m_busy = false;
 
     m_logWindow = new LogWindow;
@@ -3107,11 +3103,6 @@ void updateWatchersWindow(bool showWatch, bool showReturn)
     dd->m_returnWindow->setVisible(showReturn);
 }
 
-QIcon locationMarkIcon()
-{
-    return dd->m_locationMarkIcon;
-}
-
 bool hasSnapshots()
 {
      return dd->m_snapshotHandler->size();