Merged revisions 304638 via svnmerge from

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

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  r304638 | seanbright | 2011-01-28 15:19:08 -0500 (Fri, 28 Jan 2011) | 11 lines
  
  Restore some conditionals that we lost in r277814.
  
  There are some cases where ast_append_ha() is called with a NULL instead of a
  valid int pointer.  So if we get a NULL, don't try to dereference it.
  
  (closes issue #18162)
  Reported by: imcdona
  Patches:
        issue0018162.patch uploaded by pabelanger (license 224)
  Tested by: enegaard
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@304639 65c4cc65-6c06-0410-ace0-fbb531ad65f3