moved benchmark lox files to separate folder

benchmark/fib.lox

@@ -0,0 +1,8 @@
+fun fib(n) {
+  if (n < 2) return n;
+  return fib(n - 2) + fib(n - 1);
+}
+
+// var start = clock();
+print fib(35); // expect: 9227465
+// print clock() - start;

lox.t/fib.lox

@@ -3,6 +3,4 @@ fun fib(n) {
   return fib(n - 2) + fib(n - 1);
 }
 
-var start = clock();
+print fib(35); // expect: 9227465
-print fib(35) == 9227465;
-print clock() - start;