vircgroup: Update virCgroupGetPercpuStats stump

In the commit 7938b533 we've changed the function signature,
however forgot to update stump that's used on systems without
CGroups causing a build failure.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/util/vircgroup.c

@@ -4945,7 +4945,7 @@ virCgroupGetPercpuStats(virCgroupPtr group ATTRIBUTE_UNUSED,
                         unsigned int nparams ATTRIBUTE_UNUSED,
                         int start_cpu ATTRIBUTE_UNUSED,
                         unsigned int ncpus ATTRIBUTE_UNUSED,
-                        unsigned int nvcpupids ATTRIBUTE_UNUSED)
+                        virBitmapPtr guestvcpus ATTRIBUTE_UNUSED)
 {
     virReportSystemError(ENOSYS, "%s",
                          _("Control groups not supported on this platform"));