Fix the "forward" system test on Windows

Make sure carriage return characters are stripped from sed input to
enable the "forward" system test to pass on Windows.

bin/tests/system/forward/tests.sh

@@ -161,7 +161,7 @@ count_sent() (
 	logfile="$1"
 	start_pattern="$2"
 	pattern="$3"
-	nextpartpeek "$logfile" | sed -n "/$start_pattern/,/^\$/p" | grep -c "$pattern"
+	nextpartpeek "$logfile" | tr -d '\r' | sed -n "/$start_pattern/,/^\$/p" | grep -c "$pattern"
 )
 
 check_sent() (