Adapt to recent foundation::Tile class changes

[usakhelo]

Couple of changes required to compile against current appleseed master branch

[dictoon]

Looks good.

As I was reviewing this code I noticed that we can also remove a bunch of code a few lines above your changes. Because appleseed's frame is now always using 32-bit floating point channels, all of this code in TileCallback::blit_tile() can be removed and tile can be used directly:

// Allocate memory for the temporary tile.
if (m_float_tile_storage.get() == nullptr)
{
    m_float_tile_storage.reset(
        new asf::Tile(
            props.m_tile_width,
            props.m_tile_height,
            props.m_channel_count,
            asf::PixelFormatFloat));
}

// Retrieve the source tile.
const asf::Tile& tile = frame.image().tile(tile_x, tile_y);

// Convert the tile to 32-bit floating point.
asf::Tile fp_tile(
    tile,
    asf::PixelFormatFloat,
    m_float_tile_storage->get_storage());