Fix compile warning, make sure pickup_exten is matched in full, not partial

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4971 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix callgroup/pickupgroup setting for pre-11 asterisk versions

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4972 43c1dc8c-776e-4df2-8ef1-6e829299be21