Create strike-through wxGraphicsFont objects in wxOSX

Honour wxFONTFLAG_UNDERLINED in wxGraphicsFont::CreateFont() overload taking
flags.

See https://github.com/wxWidgets/wxWidgets/pull/187

src/osx/carbon/graphics.cpp

@@ -2875,6 +2875,9 @@ wxMacCoreGraphicsRenderer::CreateFont(double sizeInPixels,
                 (flags & wxFONTFLAG_UNDERLINED) != 0,
                 facename);
 
+    if ( flags & wxFONTFLAG_STRIKETHROUGH )
+        font.MakeStrikethrough();
+
     wxGraphicsFont f;
     f.SetRefData(new wxMacCoreGraphicsFontData(this, font, col));
     return f;