Don't leak associations in wxCocoaDataViewControl

Fix ClearColumns() to release associations between m_OutlineView and
native Cocoa control when re-creating the latter. Previously it only
created a new association, but left the old one with no-deleted native
control in the map.

Fixes #17485.

include/wx/osx/core/private.h

@@ -343,6 +343,7 @@ public :
                         FindBestFromWXWidget(WXWidget control);
     
     static void         RemoveAssociations( wxWidgetImpl* impl);
+    static void         RemoveAssociation(WXWidget control);
 
     static void         Associate( WXWidget control, wxWidgetImpl *impl );
 

src/osx/cocoa/dataview.mm

@@ -2084,6 +2084,7 @@ bool wxCocoaDataViewControl::ClearColumns()
     // as there is a bug in NSOutlineView version (OSX 10.5.6 #6555162) the
     // columns cannot be deleted if there is an outline column in the view;
     // therefore, the whole view is deleted and newly constructed:
+    RemoveAssociation(m_OutlineView); // undo InitOutlineView's association
     [m_OutlineView release];
     m_OutlineView = [[wxCocoaOutlineView alloc] init];
     [((NSScrollView*) GetWXWidget()) setDocumentView:m_OutlineView];

src/osx/window_osx.cpp

@@ -2739,6 +2739,13 @@ void wxWidgetImpl::RemoveAssociations(wxWidgetImpl* impl)
     }
 }
 
+void wxWidgetImpl::RemoveAssociation(WXWidget control)
+{
+	wxCHECK_RET( control != NULL, wxT("attempt to remove a NULL WXWidget from control map") );
+
+	wxWinMacControlList.erase(control);
+}
+
 wxIMPLEMENT_ABSTRACT_CLASS(wxWidgetImpl, wxObject);
 
 wxWidgetImpl::wxWidgetImpl( wxWindowMac* peer , bool isRootControl, bool isUserPane )