move out c/cpp/py

cl/_testlibc/once/in.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"github.com/goplus/lib/c"
+	"github.com/goplus/lib/c/pthread/sync"
+)
+
+var once sync.Once = sync.OnceInit
+
+func f() {
+	once.Do(func() {
+		c.Printf(c.Str("Do once\n"))
+	})
+}
+
+func main() {
+	println(c.GoString(c.Str("sync.Once demo\n"), 9))
+	println(c.GoString(c.Str("sync.Once demo\n")))
+	f()
+	f()
+}