Fix sizing of temporarily last columns in macOS wxDataViewCtrl

Update the column width if it used to be the last one but isn't last one
any longer.

Closes #14939.

include/wx/osx/cocoa/dataview.h

@@ -86,7 +86,7 @@ class wxCocoaDataViewControl;
 class wxDataViewColumnNativeData
 {
 public:
-    wxDataViewColumnNativeData() : m_NativeColumnPtr(NULL)
+    wxDataViewColumnNativeData() : m_NativeColumnPtr(NULL), m_isLast(false), m_prevWidth(0)
     {
     }
 
@@ -105,9 +105,32 @@ public:
         m_NativeColumnPtr = newNativeColumnPtr;
     }
 
+    bool GetIsLast() const
+    {
+        return m_isLast;
+    }
+
+    void SetIsLast(bool isLast)
+    {
+        m_isLast = isLast;
+    }
+
+    int GetPrevWidth() const
+    {
+        return m_prevWidth;
+    }
+
+    void SetPrevWidth(int prevWidth)
+    {
+        m_prevWidth = prevWidth;
+    }
+
 private:
     // not owned by us
     NSTableColumn* m_NativeColumnPtr;
+
+    bool m_isLast;
+    int m_prevWidth;
 };
 
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