Hiqnet: fix Mac OS X buildbot

Change-Id: Ia4fec86ed389ccb558fe9e1acfb6e87b7012bb75
warning: declaration of 'strlen' shadows a global declaration
Reviewed-on: https://code.wireshark.org/review/5237
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>