Fix wxGenericListCtrl build with wxUSE_STD_CONTAINERS and C++98

Use wxShrinkToFit() instead of wxVector::shrink_to_fit() which is not
defined in this build configuration.

This was broken by recent 2af7e38153.

See https://github.com/wxWidgets/wxWidgets/pull/924

src/generic/listctrl.cpp

@@ -1707,7 +1707,7 @@ wxListLineData *wxListMainWindow::GetDummyLine() const
 
         // don't waste extra memory -- there never going to be anything
         // else/more in this array
-        self->m_lines.shrink_to_fit();
+        wxShrinkToFit(self->m_lines);
     }
 
     return m_lines[0];