am a4f3e2ee: am 5d53c069: am 21499444: am 00376b4d: Avoid a harmless potential integer overflow in png_XYZ_from_xy().

* commit 'a4f3e2ee148bddf79662576e69fa067d329da4b0':
  Avoid a harmless potential integer overflow in png_XYZ_from_xy().