improve add_project_versioning_to_ffmpeg and remove HEADLESS

lib/docker.sh

@@ -19,7 +19,7 @@ set_docker_run_flags() {
         -v "${REPO_DIR}:${REPO_DIR}"
         -w "${REPO_DIR}"
         -e "DEBUG=${DEBUG}"
-        -e "HEADLESS=${HEADLESS}"
+        -t
     )
     for opt in "${FB_COMP_OPTS[@]}"; do
         declare -n defOptVal="DEFAULT_${opt}"