move out c/cpp/py

cl/_testlibgo/waitgroup/in.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"sync"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		println("work 1")
+	}()
+	go func() {
+		defer wg.Done()
+		println("work 2")
+	}()
+	wg.Wait()
+	println("done")
+}