apply patch to fix segfault on cli commond 'sccp set channel <channe> hold' (without 6th argument). Patch provied by Max Nesterov. Thank you Max

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5808 43c1dc8c-776e-4df2-8ef1-6e829299be21