Modify some of tests/test-vmstate.c due to qemu_bufopen() change.
If you create a QEMUSizedBuffer yourself, you have to explicitly
free it.
Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com> Cc: Juan Quintela <quintela@redhat.com> Cc: Amit Shah <amit.shah@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Amit Shah <amit.shah@redhat.com>