std.Io: delete BufferedWriter

[andrewrk]

Upgrade Guide

-    const stdout_file = std.fs.File.stdout().writer();
-    var bw = std.io.bufferedWriter(stdout_file);
-    const stdout = bw.writer();
+    var stdout_buffer: [4096]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
 
     try stdout.print("Run `zig build test` to run the tests.\n", .{});
 
-    try bw.flush(); // Don't forget to flush!
+    try stdout.flush(); // Don't forget to flush!

Consider making your stdout buffer global.