Fix compilation issues (I think)

I think this is from the switch to a nightly version of Zig, but not
sure.  Anyways, with this it compiles.

zig/sdl/hello_sdl.zig

                                pos = 0;
                                num_lines = 0;
                                var lines = std.mem.split(result, "\n");
                                var lines = std.mem.split(u8, result, "\n");
                                var line = lines.next();
                                while (line != null) : (line = lines.next()) {
                                    num_lines += 1;
        _ = c.SDL_RenderCopy(renderer, texture, null, &c.SDL_Rect{ .x = 0, .y = 0, .w = @intCast(c_int, msg.len) * glyph_width, .h = glyph_height });
        var i: c_int = 1;
        var lines = std.mem.split(result, "\n");
        var lines = std.mem.split(u8, result, "\n");
        var line = lines.next();
        {
            var skipped: i32 = 0;