cpu.c: Check properly for virCapabilitiesGetNodeInfo() retval

The virCapabilitiesGetNodeInfo() function has the usual return
value semantics for integeres: a negative value means an error,
zero or a positive value means success. However, the function
call done in virCPUProbeHost() doesn't check for the return value
accordingly.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NPeter Krempa <pkrempa@redhat.com>

src/cpu/cpu.c

@@ -456,7 +456,7 @@ virCPUProbeHost(virArch arch)
 {
     virNodeInfo nodeinfo;
 
-    if (virCapabilitiesGetNodeInfo(&nodeinfo))
+    if (virCapabilitiesGetNodeInfo(&nodeinfo) < 0)
         return NULL;
 
     return virCPUGetHost(arch, VIR_CPU_TYPE_HOST, &nodeinfo, NULL);