core: fix usage of uv_cwd

It was modified in libuv to be consistent with uv_exepath and not
include the trailing NULL byte in the returned size.

PR-URL: nodejs/node-v0.x-archive#8566
Reviewed-by: Fedor Indutny <fedor@indutny.com>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>

src/node.cc

@@ -1636,7 +1636,7 @@ static void Cwd(const FunctionCallbackInfo<Value>& args) {
   Local<String> cwd = String::NewFromUtf8(env->isolate(),
                                           buf,
                                           String::kNormalString,
-                                          cwd_len - 1);
+                                          cwd_len);
   args.GetReturnValue().Set(cwd);
 }