Fix GlobalProtect authgroup handling

When connecting to a GlobalProtect server via the portal interface, then
`vpninfo->authgroup` needs to be set to the URL of one of the allowed
gateways.

The problem here is that if the user actually wanted to select the _first_
gateway in the dropdown list, it was already pre-selected, and thus clicking
"continue"/"login" on the form wouldn't trigger `OC_FORM_RESULT_NEWGROUP`.

This would prevent `vpninfo->authgroup` from getting set correctly, and the
gateway redirect would be skipped entirely.  Thus it was effectively
impossible to select the first option in the gateway dropdown.

Signed-off-by: Daniel Lenski <dlenski@gmail.com>

auth-globalprotect.c

@@ -401,6 +401,8 @@ static int parse_portal_xml(struct openconnect_info *vpninfo, xmlNode *xml_node,
 				     choice->label, choice->name);
 		}
 	}
+	if (!vpninfo->authgroup && opt->nr_choices)
+		vpninfo->authgroup = strdup(opt->choices[0]->name);
 
 	if (vpninfo->write_new_config) {
 		buf_append(buf, "  </ServerList>\n</GPPortal>\n");
@@ -412,7 +414,7 @@ static int parse_portal_xml(struct openconnect_info *vpninfo, xmlNode *xml_node,
 
 	/* process auth form to select gateway */
 	result = process_auth_form(vpninfo, form);
-	if (result != OC_FORM_RESULT_NEWGROUP)
+	if (result == OC_FORM_RESULT_CANCELLED || result < 0)
 		goto out;
 
 	/* redirect to the gateway (no-op if it's the same host) */