Added check to prevent image being 0x0 (reported in #489).
static inline void VectorCopy43(const DDSVector4 source,
  DDSVector3 *destination)
{
  destination->x = source.x;
  destination->y = source.y;
  destination->z = source.z;
}

static inline void VectorCopy43(const DDSVector4 source,
  DDSVector3 *destination)
{
  destination->x = source.x;
  destination->y = source.y;
  destination->z = source.z;
}
