iotests: Disable broken streamOptimized tests

streamOptimized does not support writes that do not span exactly one
cluster.  Furthermore, it cannot rewrite already allocated clusters.
As such, many iotests do not work with it.  Disable them.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190815153638.4600-6-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/tests/qemu-iotests/034 b/tests/qemu-iotests/034
index 324bed2..da4cea1 100755
--- a/tests/qemu-iotests/034
+++ b/tests/qemu-iotests/034
@@ -41,7 +41,8 @@
 _supported_os Linux
 _unsupported_imgopts "subformat=monolithicFlat" \
                      "subformat=twoGbMaxExtentFlat" \
-                     "subformat=twoGbMaxExtentSparse"
+                     "subformat=twoGbMaxExtentSparse" \
+                     "subformat=streamOptimized"
 
 CLUSTER_SIZE=4k
 size=128M