tests: check-qom-proplist: add checks for cmdline-created objects

check-qom-proplist originally added tests for verifying that
object-creation helpers object_new_with_{props,propv} behaved in
similar fashion to the "traditional" method involving setting each
individual property separately after object creation rather than
via a single call.

Another similar "helper" for creating Objects exists in the form of
objects specified via -object command-line parameters. By that
rationale, we extend check-qom-proplist to include similar checks
for command-line-created objects by employing the same
qemu_opts_parse()-based parsing the vl.c employs.

This parser has a side-effect of parsing the object's options into
a QemuOpt structure and registering this in the global QemuOptsList
using the Object's ID. This can conflict with future Object instances
that attempt to use the same ID if we don't ensure this is cleaned
up as part of Object finalization, so we include a FIXME stub to test
for this case, which will then be resolved in a subsequent patch.

Suggested-by: Daniel Berrange <berrange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Daniel Berrange <berrange@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1496531612-22166-2-git-send-email-mdroth@linux.vnet.ibm.com>
[Comment formatting tidied up]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

(cherry picked from commit a1af255f)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>