validate: Include config.h before anything else
To avoid double-defines (such as GST_LEVEL_DEFAULT)
In file included from formatting.c:33: ../../config.h:45: error: "GST_LEVEL_DEFAULT" redefined [-Werror] #define GST_LEVEL_DEFAULT GST_LEVEL_ERROR
In file included from /home/jenkins/workspace/GStreamer-master-validate/gstreamer/gst/gst.h:55, from formatting.h:26, from formatting.c:26: /home/jenkins/workspace/GStreamer-master-validate/gstreamer/gst/gstinfo.h:102: note: this is the location of the previous definition #define GST_LEVEL_DEFAULT GST_LEVEL_NONE