Add Signal::cancel() method to remove signal that has been installed previously.
Add Signal::cancel() method to remove signal that has been
installed previously.

jevonearth/rtpproxy,sippy/rtpproxy,sippy/rtpproxy,sippy/rtpproxy,synety-jdebp/rtpproxy,dsanders11/rtpproxy,synety-jdebp/rtpproxy,sippy/rtp_cluster,synety-jdebp/rtpproxy,jevonearth/rtpproxy,synety-jdebp/rtpproxy,jevonearth/rtpproxy,sippy/rtp_cluster,dsanders11/rtpproxy,jevonearth/rtpproxy,dsanders11/rtpproxy