Merged revisions 253490 via svnmerge from

Merged revisions 253490 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

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  r253490 | alecdavis | 2010-03-19 20:37:00 +1300 (Fri, 19 Mar 2010) | 19 lines

  prevent segfault if bad magic number is encountered.

  internal_ao2_ref uses INTERNAL_OBJ which mzy report 'bad magic number', but
  internal_ao2_ref continues on, causing segfault.

  Although AO2_MAGIC number is checked by INTERNAL_OBJ before internal_ao2_ref is
  called, A02_MAGIC is being destroyed (or a wrong pointer) by the time
  internal_ao2_ref uses INTERNAL_OBJ.

  internal_ao2_ref now returns -1 if INTERNAL_OBJ encouters a bad magic number.

  (issue #17037)
  Reported by: alecdavis
  Patches:
        bug17037.diff.txt uploaded by alecdavis (license 585)
  Tested by: alecdavis
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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@253491 65c4cc65-6c06-0410-ace0-fbb531ad65f3