qemu: fix crash in qemuOpen

If the path part of connection URI is not present, cfg is used
unitialized.

https://bugzilla.redhat.com/show_bug.cgi?id=950855
(cherry picked from commit 74bff2509080912ea8abf1de8fd95fa2412b659a)
qemu: Set correct migrate host in client_migrate_info

https://bugzilla.redhat.com/show_bug.cgi?id=920441

Currently, we are discarding listen attribute from qemu cookie even though
we strive to gather it. This result in not so cool bug: if user have
different networks, one for management/migration, and one for VNC/SPICE we
pass incorrect host to the qemu in client_migrate_info. What we actually
pass is remote hostname, while we should be passing remote listen address.
It doesn't matter as long as these two are the same, but they don't need
necessary to be like that.
(cherry picked from commit 7f15ebc7a2b599ab10dbc15bca6f823591213e67)
Fix signature of dummy virNetlinkCommand stub

The second param of virNetlinkCommand should be
struct nlmsghdr, not unsigned char.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 3f85de52925111b0b015080b49138dba8919862f)
Add missing param to virCgroupForDriver stub

The virCgroupForDriver method recently gained an 'int controllers'
parameter, but the stub impl did not

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
(cherry picked from commit c9b8cdfec13b31e65bad47b94b89f09426c99c17)
conf: fix comment about parsing graphics listen address
(cherry picked from commit 9f8badbbe6800404cf16efe25a0ac73216d613ed)
qemu: fix default spice password setting

Set spice password even if default VNC password hasn't been set.

https://bugzilla.redhat.com/show_bug.cgi?id=953720
(cherry picked from commit 4327df7eee75c5bec485703eb5b5f439f2fd371f)