Allow users to specify the vmdk virtual hardware version.

Vmdk images have metadata to indicate the vmware virtual
hardware version image was created/tested to run with.
Allow users to specify that version via new 'hwversion'
option.

[ kwolf: Adjust qemu-iotests common.filter ]

Signed-off-by: Janne Karhunen <Janne.Karhunen@gmail.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-doc.texi

@@ -693,6 +693,9 @@ Supported options:
 File name of a base image (see @option{create} subcommand).
 @item compat6
 Create a VMDK version 6 image (instead of version 4)
+@item hwversion
+Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
+if hwversion is specified.
 @item subformat
 Specifies which VMDK subformat to use. Valid options are
 @code{monolithicSparse} (default),