Fix crash on OOM in parsing CPU mask in domain XML

The virDomainDefParseXML method did not check the return value
of the virBitmapNew API call for NULL. This lead to a crash on
OOM
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/conf/domain_conf.c

@@ -11188,7 +11188,8 @@ virDomainDefParseXML(xmlDocPtr xml,
             if (VIR_ALLOC(vcpupin) < 0)
                 goto error;
 
-            vcpupin->cpumask = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN);
+            if (!(vcpupin->cpumask = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN)))
+                goto error;
             virBitmapCopy(vcpupin->cpumask, def->cpumask);
             vcpupin->vcpuid = i;
             def->cputune.vcpupin[def->cputune.nvcpupin++] = vcpupin;