qemu: add capability detection for query-cpus-fast

Detect whether QEMU supports the QMP query-cpus-fast API
and set QEMU_CAPS_QUERY_CPUS_FAST in this case.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com>
Acked-by: Peter Krempa <pkrempa@redhat.com>

tests/qemucapabilitiesdata/caps_2.12.0.aarch64.xml

@@ -155,6 +155,7 @@
   <flag name='qcow2-luks'/>
   <flag name='pcie-pci-bridge'/>
   <flag name='seccomp-blacklist'/>
+  <flag name='query-cpus-fast'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>342346</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.ppc64.xml

@@ -152,6 +152,7 @@
   <flag name='dump-completed'/>
   <flag name='qcow2-luks'/>
   <flag name='seccomp-blacklist'/>
+  <flag name='query-cpus-fast'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>419215</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.s390x.xml

@@ -117,6 +117,7 @@
   <flag name='virtio-tablet-ccw'/>
   <flag name='qcow2-luks'/>
   <flag name='seccomp-blacklist'/>
+  <flag name='query-cpus-fast'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>0</microcodeVersion>

tests/qemucapabilitiesdata/caps_2.12.0.x86_64.xml

@@ -193,6 +193,7 @@
   <flag name='qcow2-luks'/>
   <flag name='pcie-pci-bridge'/>
   <flag name='seccomp-blacklist'/>
+  <flag name='query-cpus-fast'/>
   <version>2011090</version>
   <kvmVersion>0</kvmVersion>
   <microcodeVersion>390060</microcodeVersion>