Use wxVector::shrink_to_fit() directly

Don't use deprecated wxShrinkToFit() as now wxVector always has this
member function because it is available even in STL build when using
C++11.

src/generic/listctrl.cpp

@@ -1728,7 +1728,7 @@ wxListLineData *wxListMainWindow::GetDummyLine() const
 
         // don't waste extra memory -- there never going to be anything
         // else/more in this array
-        wxShrinkToFit(self->m_lines);
+        self->m_lines.shrink_to_fit();
     }
 
     return m_lines[0];