Fix segfault when '-n unix:xxx' option has been specified.
Fix segfault when '-n unix:xxx' option has been specified.

hongbinz/rtpproxy,jevonearth/rtpproxy,jevonearth/rtpproxy,synety-jdebp/rtpproxy,dsanders11/rtpproxy,Vocalocity/rtpproxy-pre,sippy/rtpproxy,hongbinz/rtpproxy,jevonearth/rtpproxy,Vocalocity/rtpproxy-pre,dsanders11/rtpproxy,sippy/rtpproxy,hongbinz/rtpproxy,synety-jdebp/rtpproxy,synety-jdebp/rtpproxy,Vocalocity/rtpproxy-pre,synety-jdebp/rtpproxy,hongbinz/rtpproxy,jevonearth/rtpproxy,Vocalocity/rtpproxy-pre,dsanders11/rtpproxy,sippy/rtpproxy