virsh secret-list leak when no secrets are defined:

==27== 8 bytes in 1 blocks are definitely lost in loss record 6 of 726
==27==    by 0x4E941DD: virAllocN (viralloc.c:183)
==27==    by 0x5037F1A: remoteConnectListAllSecrets (remote_driver.c:3076)
==27==    by 0x5004EC6: virConnectListAllSecrets (libvirt.c:16298)
==27==    by 0x15F813: vshSecretListCollect (virsh-secret.c:397)
==27==    by 0x15F0E1: cmdSecretList (virsh-secret.c:532)

And so do some other *-list commands.

https://bugzilla.redhat.com/show_bug.cgi?id=1001536