Fix exception when rtpproxy is enabled: global_config -> self.global_config.
Fix exception when rtpproxy is enabled: global_config -> self.global_config.

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