Merged revisions 304554 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

........
  r304554 | rmudgett | 2011-01-27 13:08:14 -0600 (Thu, 27 Jan 2011) | 4 lines
  
  Warning message if CALLCOMPLETION(cc_callback_macro or cc_agent_dialstring) are empty.
  
  Test if the value pointer is not NULL instead of not ast_strlen_zero().
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@304555 65c4cc65-6c06-0410-ace0-fbb531ad65f3