test: allow for different nsswitch.conf settings

The motivation for this commit is that these two test fail on systems
that have different Name Service Switch configuration settings. A
concrete example of this is when using Red Hat Enterprise Linux (RHEL)
7.

If Name Service Switch is available on the operating system then it
might be configured differently (/etc/nsswitch.conf).
If the system is configured with no dns the error code will be
AI_AGAIN, but if there are more services after the dns entry, for
example some linux distributions skip a myhostname service by default
which would still produce the ENOTFOUND error.

This commit suggests checking for either ENOTFOUND or EAI_AGAIN to
accommodate systems like the ones described above. The references below
indicate that others have run, or are running, into this aswell.

Refs: nodejs#12075
Refs: nodejs/help#687

test/parallel/test-net-better-error-messages-port-hostname.js

@@ -9,7 +9,13 @@ const c = net.createConnection(0, 'this.hostname.is.invalid');
 c.on('connect', common.mustNotCall());
 
 c.on('error', common.mustCall(function(e) {
-  assert.strictEqual(e.code, 'ENOTFOUND');
+  // If Name Service Switch is available on the operating system then it
+  // might be configured differently (/etc/nsswitch.conf).
+  // If the system is configured with no dns the error code will be EAI_AGAIN,
+  // but if there are more services after the dns entry, for example some
+  // linux distributions ship a myhostname service by default which would
+  // still produce the ENOTFOUND error.
+  assert.ok(e.code === 'ENOTFOUND' || e.code === 'EAI_AGAIN');
   assert.strictEqual(e.port, 0);
   assert.strictEqual(e.hostname, 'this.hostname.is.invalid');
 }));

test/parallel/test-net-connect-immediate-finish.js

@@ -32,7 +32,13 @@ const client = net.connect({
 client.once('error', common.mustCall((err) => {
   assert(err);
   assert.strictEqual(err.code, err.errno);
-  assert.strictEqual(err.code, 'ENOTFOUND');
+  // If Name Service Switch is available on the operating system then it
+  // might be configured differently (/etc/nsswitch.conf).
+  // If the system is configured with no dns the error code will be EAI_AGAIN,
+  // but if there are more services after the dns entry, for example some
+  // linux distributions ship a myhostname service by default which would
+  // still produce the ENOTFOUND error.
+  assert.ok(err.code === 'ENOTFOUND' || err.code === 'EAI_AGAIN');
   assert.strictEqual(err.host, err.hostname);
   assert.strictEqual(err.host, 'this.hostname.is.invalid');
   assert.strictEqual(err.syscall, 'getaddrinfo');