Implement bhyveConnectBaselineCPU to support OpenStack/Nova

nmdm is a FreeBSD driver which allows to create a pair of tty
devices one of which is passed to the guest and second is used
by the client.

This patch adds new 'nmdm' character device type. Its definition
looks this way:

<serial type='nmdm'>
  <source master='/dev/nmdm0A' slave='/dev/nmdm0B'/>
</serial>

Master is passed to the hypervisior and slave is used for client
connection.

Also implement domainOpenConsole() for bhyve driver based on that.

Signed-off-by: NRoman Bogorodskiy <bogorodskiy@gmail.com>

Implement domain lookup by its ID.

The only supported flag for now is 'autodestroy'. In order to
support 'autodestroy', add support for close callbacks.

Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

New functionalities:
- connectGetMaxVcpus - on bhyve hardcode this value to 16
- nodeGetFreeMemory - do not use physmem_get on FreeBSD, since
                      it might get wrong value on systems with
                      more than 100GB of RAM
- nodeGetCPUMap - wrapper only for mapping function, currently not
                  supported by FreeBSD
- nodeSet/GetMemoryParameters - wrapper only for future improvements,
                                currently not supported by FreeBSD

Any source file which calls the logging APIs now needs
to have a VIR_LOG_INIT("source.name") declaration at
the start of the file. This provides a static variable
of the virLogSource type.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Add a check that domain is active before attempting to destroy it.

Add bhyveNodeGetInfo() which is a simple wrapper around nodeGetInfo()
from src/nodeinfo.c.

Coverity found an issue in lxc_driver and uml_driver that we don't
check the return value of register functions.

I've also updated all other places and unify the way we check the
return value.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Implement domainUndefine and required helper functions:
 - domainIsActive
 - domainIsPersistent

- Implement nodeGetCPUStats using nodeGetCPUStats()
- Implement nodeGetMemoryStats using nodeGetMemoryStats()

At this point it has a limited functionality and is highly
experimental. Supported domain operations are:

  * define
  * start
  * destroy
  * dumpxml
  * dominfo

It's only possible to have only one disk device and only one
network, which should be of type bridge.