Account for pad hole is BBox

The bounding box is used for hit testing.  If the hole is arbitrarily
larger than the pad, we need to allow the user to properly select it

pcbnew/pad.cpp

@@ -486,6 +486,10 @@ void PAD::BuildEffectiveShapes( PCB_LAYER_ID aLayer ) const
 
     m_effectiveHoleShape = std::make_shared<SHAPE_SEGMENT>( m_pos - half_len, m_pos + half_len,
                                                             half_width * 2 );
+    bbox = m_effectiveHoleShape->BBox();
+    m_effectiveBoundingBox.Merge(
+            EDA_RECT( (wxPoint) bbox.GetPosition(),
+                    wxSize( bbox.GetWidth(), bbox.GetHeight() ) ) );
 
     // All done
     m_shapesDirty = false;