Add support for timestamping QEMU logs

QEMU commit 5e2ac51 added a boolean '-msg timestamp=[on|off]'
option, which can enable timestamps on errors:
$ qemu-system-x86_64 -msg timestamp=on zghhdorf
2014-04-09T13:25:46.779484Z qemu-system-x86_64: -msg timestamp=on: could
not open disk image zghhdorf: Could not open 'zghhdorf': No such file or
directory

Enable this timestamp if the QEMU binary supports it.

Add a 'log_timestamp' option to qemu.conf for disabling this behavior.

tests/qemucapabilitiesdata/caps_1.6.0-1.caps

@@ -143,4 +143,5 @@
     <flag name='spiceport'/>
     <flag name='usb-kbd'/>
     <flag name='host-pci-multidomain'/>
+    <flag name='msg-timestamp'/>
   </qemuCaps>

tests/qemucapabilitiesdata/caps_1.6.50-1.caps

@@ -141,4 +141,5 @@
     <flag name='spiceport'/>
     <flag name='usb-kbd'/>
     <flag name='host-pci-multidomain'/>
+    <flag name='msg-timestamp'/>
   </qemuCaps>

tests/qemuxml2argvdata/qemuxml2argv-minimal-msg-timestamp.args

@@ -0,0 +1,6 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
+/usr/bin/qemu \
+-name QEMUGuest1 -S -M pc -m 214 -smp 1 -nographic -monitor \
+unix:/tmp/test-monitor,server,nowait -no-acpi -boot c \
+-usb -hda /dev/HostVG/QEMUGuest1 -net none -serial \
+none -parallel none -msg timestamp=on

tests/qemuxml2argvdata/qemuxml2argv-minimal-msg-timestamp.xml

@@ -0,0 +1,32 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <title>A description of the test machine.</title>
+  <description>
+      A test of qemu&apos;s minimal configuration.
+      This test also tests the description and title elements.
+  </description>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static' cpuset='1-4,8-20,525'>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'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -578,6 +578,7 @@ mymain(void)
     unsetenv("SDL_AUDIODRIVER");
 
     DO_TEST("minimal", QEMU_CAPS_NAME);
+    DO_TEST("minimal-msg-timestamp", QEMU_CAPS_NAME, QEMU_CAPS_MSG_TIMESTAMP);
     DO_TEST("minimal-s390", QEMU_CAPS_NAME);
     DO_TEST("machine-aliases1", NONE);
     DO_TEST("machine-aliases2", QEMU_CAPS_KVM);