test: map/slice clear

cl/_testrt/clear/in.go

@@ -0,0 +1,11 @@
+package clear
+
+func Clear() {
+	a := []int{1, 2, 3, 4}
+	clear(a)
+	println(a)
+
+	b := map[int]int{1: 1, 2: 2, 3: 3, 4: 4}
+	clear(b)
+	println(b)
+}