implement integer division tests

src/test/test.k

@@ -10,6 +10,10 @@ function mul(x: int, y: int): int {
   return (x * y);
 }
 
+function div(x: int, y: int): int {
+  return (x / y);
+}
+
 function modulo(x: int, y: int): int {
   return (x % y);
 }