Merged revisions 308622 via svnmerge from

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

........
  r308622 | rmudgett | 2011-02-23 17:38:04 -0600 (Wed, 23 Feb 2011) | 9 lines
  
  sig_pri_new_ast_channel() should return NULL when new_ast_channel() fails.
  
  (closes issue #18874)
  Reported by: cmaj
  Patches:
        patch-sig_pri-crash-possible-null-channel-pointer.diff.txt uploaded by cmaj (license 830)
  
  JIRA SWP-3172
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@308623 65c4cc65-6c06-0410-ace0-fbb531ad65f3