[OpenSIPS-Devel] [OpenSIPS/opensips] 249b80: [nathelper] Fix bad test on resolving flag name

[Bogdan Andrei IANCU]

  Branch: refs/heads/master
  Home:   https://github.com/OpenSIPS/opensips
  Commit: 249b80741ddbb0952c7f737af2a7c2473f05eacf
      https://github.com/OpenSIPS/opensips/commit/249b80741ddbb0952c7f737af2a7c2473f05eacf
  Author: Bogdan-Andrei Iancu <bogdan at opensips.org>
  Date:   2020-07-15 (Wed, 15 Jul 2020)

  Changed paths:
    M modules/nathelper/nathelper.c

  Log Message:
  -----------
  [nathelper] Fix bad test on resolving flag name

get_flag_id_by_name() may also return other negative codes than -1

Reported by coverity CID 200026, 200005, 199906