Tests: Don't hide unexpected error messages in test_files.sh.

Hiding them makes no sense since normally there's no error
when testing the "good" files. With "bad" files errors are
expected and then it makes sense to keep the messages hidden.

tests/test_files.sh

@@ -21,7 +21,7 @@ fi
 
 for I in "$srcdir"/files/good-*.xz
 do
-	if test -z "$XZ" || "$XZ" -dc "$I" > /dev/null 2>&1; then
+	if test -z "$XZ" || "$XZ" -dc "$I" > /dev/null; then
 		:
 	else
 		echo "Good file failed: $I"
@@ -29,7 +29,7 @@ do
 		exit 1
 	fi
 
-	if test -z "$XZDEC" || "$XZDEC" "$I" > /dev/null 2>&1; then
+	if test -z "$XZDEC" || "$XZDEC" "$I" > /dev/null; then
 		:
 	else
 		echo "Good file failed: $I"