LibCore: Call setgrent before looping on groups in get_extra_gids

Author: https://github.com/setepenre
Commit: 56010379f9
Pull-request: https://github.com/SerenityOS/serenity/pull/6734
Reviewed-by: https://github.com/bcoles
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibCore/Account.cpp

@@ -43,6 +43,7 @@ static Vector<gid_t> get_extra_gids(const passwd& pwd)
 {
     StringView username { pwd.pw_name };
     Vector<gid_t> extra_gids;
+    setgrent();
     for (auto* group = getgrent(); group; group = getgrent()) {
         if (group->gr_gid == pwd.pw_gid)
             continue;