Update extensions.conf.sample file to fix incorrect extensions.

(closes issue #15857)
Reported by: pprindeville
Patches:
      stdexten.patch#2 uploaded by pprindeville (license 347)
Tested by: pprindeville

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@227162 65c4cc65-6c06-0410-ace0-fbb531ad65f3