test: add dns memory error test

Add test that confirms that when libuv reports a memory error on a DNS
query, that the memory error is passed through and not replaced with
ENOTFOUND.

test/parallel/test-dns-memory-error.js

@@ -0,0 +1,15 @@
+// Flags: --expose-internals
+'use strict';
+
+// Check that if libuv reports a memory error on a DNS query, that the memory
+// error is passed through and not replaced with ENOTFOUND.
+
+require('../common');
+
+const assert = require('assert');
+const errors = require('internal/errors');
+
+const { UV_EAI_MEMORY } = process.binding('uv');
+const memoryError = errors.dnsException(UV_EAI_MEMORY, 'fhqwhgads');
+
+assert.strictEqual(memoryError.code, 'EAI_MEMORY');