nodeinfo: Add check and workaround to guarantee valid cpu topologies

Lately there were a few reports of the output of the virsh nodeinfo
command being inaccurate. This patch tries to avoid that by checking if
the topology actually makes sense. If it doesn't we then report a
synthetic topology that indicates to the user that the host capabilities
should be checked for the actual topology.

include/libvirt/libvirt.h.in

@@ -531,17 +531,19 @@ typedef virTypedParameter *virTypedParameterPtr;
 typedef struct _virNodeInfo virNodeInfo;
 
 struct _virNodeInfo {
-    char model[32];     /* string indicating the CPU model */
-    unsigned long memory;/* memory size in kilobytes */
-    unsigned int cpus;  /* the number of active CPUs */
-    unsigned int mhz;   /* expected CPU frequency */
-    unsigned int nodes; /* the number of NUMA cell, 1 for unusual NUMA
-                           topologies or uniform memory access; check
-                           capabilities XML for the actual NUMA topology */
-    unsigned int sockets;/* number of CPU sockets per node if nodes > 1,
-                            total number of CPU sockets otherwise */
-    unsigned int cores; /* number of cores per socket */
-    unsigned int threads;/* number of threads per core */
+    char model[32];       /* string indicating the CPU model */
+    unsigned long memory; /* memory size in kilobytes */
+    unsigned int cpus;    /* the number of active CPUs */
+    unsigned int mhz;     /* expected CPU frequency */
+    unsigned int nodes;   /* the number of NUMA cell, 1 for unusual NUMA
+                             topologies or uniform memory access; check
+                             capabilities XML for the actual NUMA topology */
+    unsigned int sockets; /* number of CPU sockets per node if nodes > 1,
+                             1 in case of unusual NUMA topology */
+    unsigned int cores;   /* number of cores per socket, total number of
+                             processors in case of unusual NUMA topology*/
+    unsigned int threads; /* number of threads per core, 1 in case of
+                             unusual numa topology */
 };
 
 /**