Handle failure of ast_calloc when allocating interfaces in res_smdi (issue...

Handle failure of ast_calloc when allocating interfaces in res_smdi (issue #7344 reported by casper)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@34495 65c4cc65-6c06-0410-ace0-fbb531ad65f3