Define _GNU_SOURCE on linux to get rid of the "vasprintf() not defined" warning.
Define _GNU_SOURCE on linux to get rid of the "vasprintf() not
defined" warning.

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