test: move cgo demo into _testgo, and make links

_demo/cgocfiles

@@ -0,0 +1 @@
+../cl/_testgo/cgocfiles

_demo/cgocfiles/cgocfiles.go

@@ -1,15 +0,0 @@
-package main
-
-/*
-#include "in.h"
-*/
-import "C"
-import "fmt"
-
-func main() {
-	r := C.test_structs(&C.s4{a: 1}, &C.s8{a: 1, b: 2}, &C.s12{a: 1, b: 2, c: 3}, &C.s16{a: 1, b: 2, c: 3, d: 4}, &C.s20{a: 1, b: 2, c: 3, d: 4, e: 5})
-	fmt.Println(r)
-	if r != 35 {
-		panic("test_structs failed")
-	}
-}

_demo/cgocfiles/in.c

@@ -1,12 +0,0 @@
-#include <stdio.h>
-#include "in.h"
-
-int test_structs(s4* s4, s8* s8, s12* s12, s16* s16, s20* s20) {
-  printf("s4.a: %d\n", s4->a);
-  printf("s8.a: %d, s8.b: %d\n", s8->a, s8->b);
-  printf("s12.a: %d, s12.b: %d, s12.c: %d\n", s12->a, s12->b, s12->c);
-  printf("s16.a: %d, s16.b: %d, s16.c: %d, s16.d: %d\n", s16->a, s16->b, s16->c, s16->d);
-  printf("s20.a: %d, s20.b: %d, s20.c: %d, s20.d: %d, s20.e: %d\n", s20->a, s20->b, s20->c, s20->d, s20->e);
-
-  return s4->a + s8->a + s8->b + s12->a + s12->b + s12->c + s16->a + s16->b + s16->c + s16->d + s20->a + s20->b + s20->c + s20->d + s20->e;
-}

_demo/cgocfiles/in.h

@@ -1,33 +0,0 @@
-#pragma once
-
-typedef struct {
-	int a;
-} s4;
-
-typedef struct {
-  int a;
-  int b;
-} s8;
-
-typedef struct {
-  int a;
-  int b;
-  int c;
-} s12;
-
-typedef struct {
-  int a;
-  int b;
-  int c;
-  int d;
-} s16;
-
-typedef struct {
-  int a;
-  int b;
-  int c;
-  int d;
-  int e;
-} s20;
-
-extern int test_structs(s4* s4, s8* s8, s12* s12, s16* s16, s20* s20);