Fix memory stomping bug in astman.

Fix memory stomping bug in astman.

This memset complained in dev mod on my Ubuntu box. The memset is both
unnecessary and dangerous. At this point, m hasn't been initialized
yet, so the memset will write off to whatever address happens to be
on the stack at the time.
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Merged revisions 409077 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 409083 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/12@409087 65c4cc65-6c06-0410-ace0-fbb531ad65f3