Remove old test.

tests/concurrency_test.sh

-#!/usr/bin/env bash
-
-which valgrind
-
-check() {
-	#echo "CHECK $1 $2"
-	if [ "$1" -ne 0 ]; then
-		echo >&2 "$2"
-		exit $1
-	fi
-}
-
-to="timeout -s INT 30 "
-valgrind="valgrind --tool=helgrind --error-exitcode=1"
-
-$to $valgrind ./receiver -p 5000 -r 127 -o receiver.csv &
-$to $valgrind ./sender -t 127.0.0.1 -p 5000 -r 127 -o sender.csv
-check "$?" "sender failed"
-
-wait
-check "$?" "receiver failed"
-