While Xen only has a single paravirt console, UML, and
QEMU both support multiple paravirt consoles. The LXC
driver can also be trivially made to support multiple
consoles. This patch extends the XML to allow multiple
<console> elements in the XML. It also makes the UML
and QEMU drivers support this config.

* src/conf/domain_conf.c, src/conf/domain_conf.h: Allow
  multiple <console> devices
* src/lxc/lxc_driver.c, src/xen/xen_driver.c,
  src/xenxs/xen_sxpr.c, src/xenxs/xen_xm.c: Update for
  internal API changes
* src/security/security_selinux.c, src/security/virt-aa-helper.c:
  Only label consoles that aren't a copy of the serial device
* src/qemu/qemu_command.c, src/qemu/qemu_driver.c,
  src/qemu/qemu_process.c, src/uml/uml_conf.c,
  src/uml/uml_driver.c: Support multiple console devices
* tests/qemuxml2xmltest.c, tests/qemuxml2argvtest.c: Extra
  tests for multiple virtio consoles. Set QEMU_CAPS_CHARDEV
  for all console /channel tests
* tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args,
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args
  tests/qemuxml2argvdata/qemuxml2argv-console-virtio.args: Update
  for correct chardev syntax
* tests/qemuxml2argvdata/qemuxml2argv-console-virtio-many.args,
  tests/qemuxml2argvdata/qemuxml2argv-console-virtio-many.xml: New
  test file

* tests/qemuxml2argvdata/qemuxml2argv-*.args: Reflect reserved VGA
port change.

This patch teaches testutil how to read multi-line input files with
backspace-newline line continuation markers.

The patch also breaks up all the single-line arguments test input files into
multi-line files with lines shorter than 80 characters.

* src/qemu/qemu_command.c (qemuBuildChrChardevStr): Alter the
chardev alias.
(qemuBuildCommandLine): Output an id for the chardev counterpart.
* tests/qemuxml2argvdata/*: Update tests to match.
Reported by Daniel P. Berrange.

As noticed by Eric, commit 8e28c5d4,
which fixed generation of virtio-serial port numbers, forgot to adjust
test files which resulted in make check failure.

To try and ensure that people upgrading from old QEMU get guests
with the same PCI device ordering, change the way we assign addrs
to match QEMU's default order. This should make Windows less
annoyed.

* src/qemu/qemu_conf.c: Follow QEMU's default PCI ordering
  logic when assigning addresses
* tests/*.args: Update for changed PCI addresses

We already use the '-nodefaults' command line arg with QEMU to stop
it adding any default devices to guests. Unfortunately, QEMU will
load global config files from /etc/qemu that may also add default
devices. These aren't blocked by '-nodefaults', so we need to also
add the '-nodefconfig' arg to prevent that.

Unfortunately these global config files are also used to define
custom CPU models. So in blocking global hardware device addition
we also block definitions of new CPU models. Libvirt doesn't know
about these custom CPU models though, so it would never make use
of them anyway. Thus blocking them via -nodefconfig isn't a show
stopping problem. We would need to expand libvirt's own CPU model
XML database to support these instead.

* src/qemu/qemu_conf.c: Add '-nodefconfig' if available
* tests/qemuxml2argvdata/: Add '-nodefconfig' to all data files which
  have '-nodefaults' present

The virtio serial changes broke the test suite because they forgot
to add the new address attribute to the domain XML schema. The
xml2xml test also broke because the XML no longer roundtrips. This
is due to testing of auto-addition of <controller> elements. Split
that test case off into a separate XML file to avoid breakage

* docs/schemas/domain.rng: Allow port number for virtio serial addresses
* tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args,
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml: Revert to
  a simple config to avoid breaking xml2xml test
* tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.xml,
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args: Add
  complex test case for auto-controller addition for xml2argv test
* tests/qemuxml2argvtest.c: Add channel-virtio-auto test

The domain parsing code would auto-add a virtio serial controller
if it saw any virtio serial channel defined. Unfortunately it
always added a controller with index=0, even if the channel address
specified an index != 0. It only added one controller, even if
multiple controllers were referenced by channels. Finally, it let
the ports+vectors parameters initialize to zero instead of -1, which
prevented the controllers accepting any ports.

* src/conf/domain_conf.c: Initialize ports+vectors when adding
  virtio serial controllers. Add all neccessary virtio serial
  controllers, instead of hardcoding controller 0
* qemuxml2argvdata/qemuxml2argv-channel-virtio.args,
  qemuxml2argvdata/qemuxml2argv-channel-virtio.xml: Expand to
  test controller auto-add behaviour

To ensure that the device addressing scheme is stable across
hotplug/unplug, all virtio serial channels needs to have an
associated port number in their address. This is then specified
to QEMU using the nr=NNN parameter

* src/conf/domain_conf.c, src/conf/domain_conf.h: Parsing
  for port number in vioserial address types.
* src/qemu/qemu_conf.c: Set 'nr=NNN' parameter with virtio
  serial port number
* tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args,
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml: Expand
  data set to ensure coverage of port addressing

Support virtio-serial controller and virtio channel in QEMU backend.
Will output
the following for virtio-serial controller:

-device
virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4,max_ports=16,vectors=4

and the following for a virtio channel:

-chardev pty,id=channel0 \
-device
virtserialport,bus=virtio-serial0.0,chardev=channel0,name=org.linux-kvm.port.0

* src/qemu/qemu_conf.c: Add argument output for virtio
* tests/qemuxml2argvtest.c
  tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args: Add test for
  QEMU command line generation