stream: add custom inspect to BufferList

Currently inspecting the BufferList can result a maximum call stack
size error. Adding a individual inspect function prevents this.

PR-URL: #17907
Refs: #12693
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

lib/internal/streams/BufferList.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const { Buffer } = require('buffer');
+const { inspect } = require('util');
 
 function copyBuffer(src, target, offset) {
   Buffer.prototype.copy.call(src, target, offset);
@@ -73,4 +74,9 @@ module.exports = class BufferList {
     }
     return ret;
   }
+
+  [inspect.custom]() {
+    const obj = inspect({ length: this.length });
+    return `${this.constructor.name} ${obj}`;
+  }
 };