iotests: Make 091 work with data_file

The image end offset as reported by qemu-img check is different when
using an external data file; we do not care about its value here, so we
can just filter it.  Incidentally, common.rc already has _check_test_img
for us which does exactly that.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-id: 20191107163708.833192-18-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/091

@@ -101,7 +101,7 @@ echo "Check image pattern"
 ${QEMU_IO} -c "read -P 0x22 0 4M" "${TEST_IMG}" | _filter_testdir | _filter_qemu_io
 
 echo "Running 'qemu-img check -r all \$TEST_IMG'"
-"${QEMU_IMG}" check -r all "${TEST_IMG}" 2>&1 | _filter_testdir | _filter_qemu
+_check_test_img -r all
 
 echo "*** done"
 rm -f $seq.full

tests/qemu-iotests/091.out

@@ -23,6 +23,4 @@ read 4194304/4194304 bytes at offset 0
 4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Running 'qemu-img check -r all $TEST_IMG'
 No errors were found on the image.
-80/16384 = 0.49% allocated, 0.00% fragmented, 0.00% compressed clusters
-Image end offset: 5570560
 *** done