Don't enable IPv4 *only* on nginx.

The current configuration sample files only enable IPv4 by default, making the
server inaccesible for many remote hosts (and an increasing amount every day).

Enable IPv4 and IPv6 by default. Older servers with no external IPv6
connectivity will not fail since they'll have a local-link IPv6 address to bind
to anyway.

lib/support/nginx/gitlab

@@ -33,7 +33,8 @@ upstream gitlab {
 
 ## Normal HTTP host
 server {
-  listen *:80 default_server;
+  listen 0.0.0.0:80 default_server;
+  listen [::]:80 default_server;
   server_name YOUR_SERVER_FQDN; ## Replace this with something like gitlab.example.com
   server_tokens off; ## Don't show the nginx version number, a security best practice
   root /home/git/gitlab/public;

lib/support/nginx/gitlab-ssl

@@ -39,7 +39,8 @@ upstream gitlab {
 
 ## Normal HTTP host
 server {
-  listen *:80 default_server;
+  listen 0.0.0.0:80;
+  listen [::]:80 default_server;
   server_name YOUR_SERVER_FQDN; ## Replace this with something like gitlab.example.com
   server_tokens off; ## Don't show the nginx version number, a security best practice
 
@@ -50,7 +51,8 @@ server {
 
 ## HTTPS host
 server {
-  listen 443 ssl;
+  listen 0.0.0.0:443 ssl;
+  listen [::]:443 ssl default_server;
   server_name YOUR_SERVER_FQDN; ## Replace this with something like gitlab.example.com
   server_tokens off;
   root /home/git/gitlab/public;