The patch adds <cpu> element to domain capabilities XML:
<cpu>
<mode name='host-passthrough' supported='yes'/>
<mode name='host-model' supported='yes'/>
<mode name='custom' supported='yes'>
<model>Broadwell</model>
<model>Broadwell-noTSX</model>
...
</mode>
</cpu>
Applications can use it to inspect what CPU configuration modes are
supported for a specific combination of domain type, emulator binary,
guest architecture and machine type.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>