[NetworkManager-openconnect] Use openconnect_set_useragent() where available

[David Woodhouse <dwmw2 src gnome org>]

commit bad2d616d2bced3a83ad689daaadb25eed84931b
Author: David Woodhouse <dwmw2 infradead org>
Date:   Fri Apr 29 17:10:24 2022 +0100

    Use openconnect_set_useragent() where available

 auth-dialog/main.c | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/auth-dialog/main.c b/auth-dialog/main.c
index 305b568..8aca03f 100644
--- a/auth-dialog/main.c
+++ b/auth-dialog/main.c
@@ -1889,6 +1889,15 @@ static auth_ui_data *init_ui_data (char *vpn_name, GHashTable *options, GHashTab
                                                           nm_process_auth_form, write_progress,
                                                           ui_data);
 
+#if OPENCONNECT_CHECK_VER(5,8)
+       /* The useragent provided to openconnect_vpninfo_new() gets the
+        * OpenConnect version appended to it. But some servers need the
+        * useragent to *precisely* match a known string; support for
+        * that was added in OpenConnect 9.00 (API 5.8) with the
+        * openconnect_set_useragent() function. */
+       if (vpn_useragent)
+               openconnect_set_useragent(ui_data->vpninfo, vpn_useragent);
+#endif
 #if OPENCONNECT_CHECK_VER(5,7)
        openconnect_set_webview_callback(ui_data->vpninfo, open_webview);
 #endif