Merged revisions 324237 via svnmerge from

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

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  r324237 | twilson | 2011-06-20 12:33:07 -0500 (Mon, 20 Jun 2011) | 12 lines
  
  Ignore media offers with a port of 0
  
  Section 5.1 of RFC3264 states:
    A port number of zero in the offer indicates that the stream is offered
    but MUST NOT be used.
  
  (closes issue ASTERISK-17845)
  Reported by: jacco
  Patches: 
        issue19281_2.patch uploaded by jacco (license 1277)
  Tested by: jacco, twilson
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