res_musiconhold.c: Remove obsolete REF_DEBUG code.

Remove unneeded code that writes to the wrong file location in an obsolete
format.
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Merged revisions 421799 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 421800 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 421801 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421802 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@421803 65c4cc65-6c06-0410-ace0-fbb531ad65f3