qemu-iotests: Add _unsupported_imgopts for vmdk subformats

Some cases are not applicable for vmdk subformats those don't support
certain features, e.g. backing file, and some others can't run on
mult-file image, e.g. monolithicFlat. This adds declaration in test
cases to skip them automatically, so that iotests on vmdk can go
more smoothly (without manually picking of cases for each subformat).

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/tests/qemu-iotests/063 b/tests/qemu-iotests/063
index 2ab8f20..77503a2 100755
--- a/tests/qemu-iotests/063
+++ b/tests/qemu-iotests/063
@@ -44,6 +44,9 @@
 _supported_fmt qcow qcow2 vmdk qed raw
 _supported_proto generic
 _supported_os Linux
+_unsupported_imgopts "subformat=monolithicFlat" \
+                     "subformat=twoGbMaxExtentFlat" \
+                     "subformat=twoGbMaxExtentSparse"
 
 _make_test_img 4M