Remove plain Racket echo server comparison implementation.

marketplace/examples/echo-racket.rkt

@@ -1,15 +0,0 @@
-#lang racket
-
-(define (connection-handler cin cout)
-  (let loop ()
-    (define ch (read-char cin))
-    (when (not (eof-object? ch))
-      (display ch cout)
-      (flush-output cout)
-      (loop))))
-
-(let ((listener (tcp-listen 5999 4 #t)))
-  (let loop ()
-    (define-values (cin cout) (tcp-accept listener))
-    (thread (lambda () (connection-handler cin cout)))
-    (loop)))