virnuma: Use numa_nodes_ptr when checking available NUMA nodes

In v6.7.0-rc1~86 I've tried to fix a problem where we were not
detecting NUMA nodes properly because we misused behaviour of a
libnuma API and as it turned out the behaviour was correct for
hosts with 64 CPUs in one NUMA node. So I changed the code to use
nodemask_isset(&numa_all_nodes, ..) instead and it fixed the
problem on such hosts. However, what I did not realize is that
numa_all_nodes does not reflect all NUMA nodes visible to
userspace, it contains only those nodes that the process
(libvirtd) an allocate memory from, which can be only a subset of
all NUMA nodes. The bitmask that contains all NUMA nodes visible
to userspace and which one I should have used is: numa_nodes_ptr.
For curious ones:

4a22f22382

And as I was fixing virNumaGetNodeCPUs() I came to realize that
we already have a function that wraps the correct bitmask:
virNumaNodeIsAvailable().

Fixes: 24d7d85208f812a45686b32a0561cc9c5c9a49c9
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1876956
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

src/util/virnuma.c

@@ -260,7 +260,7 @@ virNumaGetNodeCPUs(int node,
 
     *cpus = NULL;
 
-    if (!nodemask_isset(&numa_all_nodes, node)) {
+    if (!virNumaNodeIsAvailable(node)) {
         VIR_DEBUG("NUMA topology for cell %d is not available, ignoring", node);
         return -2;
     }