[libvirt] Failure to probe cpu definitions for e.g. qemu-system-mips

[Guido Günther]

Hi,
while looking into a regression failing to start any mips qemu systems
(http://bugs.debian.org/854125) I noticed that querying cpu definition
does not work for lots of non intel architectures like mips due to lack
of support for the query-cpu-definition monitor command:

2017-03-15 04:23:55.336+0000: 4238: warning : virQEMUCapsLogProbeFailure:4838 : Failed to probe capabilities for /usr/bin/qemu-system-mips: internal error: unable to execute QEMU command 'query-cpu-definitions': The command query-cpu-definitions has not been found
2017-03-15 04:23:55.374+0000: 4238: error : qemuMonitorJSONCheckError:387 : internal error: unable to execute QEMU command 'query-cpu-definitions': The command query-cpu-definitions has not been found

Is support for query-cpu-definition a hard requirement or should we fail
gracefully in this case? If not  I can look into restoring that
behaviour but would be happy about pointers what would be the best way
forward.
Cheers,
 -- Guido