vircgroupv2: fix virCgroupV2ValidateMachineGroup

When libvirt is reconnecting to running domain that uses cgroup v2
the QEMU process reports cgroup for the emulator directory because the
main thread is in that cgroup.  We need to remove the "/emulator" part
in order to match with the root cgroup directory name for that domain.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/util/vircgroupv2.c

@@ -120,6 +120,13 @@ virCgroupV2ValidateMachineGroup(virCgroupPtr group,
 
     if (!(tmp = strrchr(group->unified.placement, '/')))
         return false;
+
+    if (STREQ(tmp, "/emulator")) {
+        *tmp = '\0';
+
+        if (!(tmp = strrchr(group->unified.placement, '/')))
+            return false;
+    }
     tmp++;
 
     if (STRNEQ(tmp, partmachinename) &&