iotests: Pull _filter_actual_image_size from 67/87

Tests 067 and 087 filter the actual image size because it depends on the
host filesystem (and is not part of the respective test).  Since this is
generally true, we should have a common filter function for this, so
let's pull out the sed line from both tests into such a function.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20171009163456.485-2-mreitz@redhat.com
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>

tests/qemu-iotests/067

@@ -56,7 +56,7 @@ _filter_qmp_events()
 function run_qemu()
 {
     do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qmp | _filter_qemu \
-                          | sed -e 's/\("actual-size":\s*\)[0-9]\+/\1SIZE/g' \
+                          | _filter_actual_image_size \
                           | _filter_generated_node_ids | _filter_qmp_events
 }
 

tests/qemu-iotests/087

@@ -46,7 +46,7 @@ function run_qemu()
 {
     do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qmp \
                           | _filter_qemu | _filter_imgfmt \
-                          | sed -e 's/\("actual-size":\s*\)[0-9]\+/\1SIZE/g'
+                          | _filter_actual_image_size
 }
 
 size=128M

tests/qemu-iotests/common.filter

@@ -105,6 +105,12 @@ _filter_block_job_len()
     sed -e 's/, "len": [0-9]\+,/, "len": LEN,/g'
 }
 
+# replace actual image size (depends on the host filesystem)
+_filter_actual_image_size()
+{
+    sed -s 's/\("actual-size":\s*\)[0-9]\+/\1SIZE/g'
+}
+
 # replace driver-specific options in the "Formatting..." line
 _filter_img_create()
 {