While in the long term we want throttling to be its own block filter
BDS, in the short term we want it to be part of the BB instead of a BDS;
even in the long term we may want legacy throttling to be automatically
tied to the BB.

blockdev-insert-medium and blockdev-remove-medium do not retain
throttling information in the BB (deliberately so). Therefore, using
them means tying this information to a BDS, which would break the model
described above. (The same applies to other flags such as
detect_zeroes.) We probably want to move this information to the BB or
its own filter BDS before blockdev-{insert,remove}-medium can be
considered completely stable.

Therefore, mark these functions experimental for the time being.
Suggested-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Acked-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1449847385-13986-2-git-send-email-mreitz@redhat.com
Reviewed-by: NEric Blake <eblake@redhat.com>
[PMM: fixed format nit (underlining) in qmp-commands.hx]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>