Make QEMU driver use -chardev everywhere if available

Change -monitor, -serial and -parallel output to use -chardev if it is
available.
* src/qemu/qemu_conf.c: Update qemudBuildCommandLine to use -chardev where
  available.
* tests/qemuxml2argvtest.c tests/qemuxml2argvdata/: Add -chardev equivalents
  for all current serial and parallel tests.

tests/qemuxml2argvdata/qemuxml2argv-parallel-tcp-chardev.xml

@@ -0,0 +1,27 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory>219200</memory>
+  <currentMemory>219200</currentMemory>
+  <vcpu>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+    </disk>
+    <parallel type='tcp'>
+      <source mode='bind' host='127.0.0.1' service='9999'/>
+      <protocol type='raw'/>
+      <target port='0'/>
+    </parallel>
+  </devices>
+</domain>