virsh: do not assign negative values to niothreads

Use a temporary 'rc' variable to avoid comparing signed
and unsigned integers in the cleanup section.

Bug introduced by commit 3072ded3 which added the comparison against
the unsigned 'i'.

Also make niothreads size_t to mark that it should be unsigned.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

tools/virsh-domain.c

@@ -7531,7 +7531,7 @@ cmdIOThreadInfo(vshControl *ctl, const vshCmd *cmd)
     bool config = vshCommandOptBool(cmd, "config");
     bool live = vshCommandOptBool(cmd, "live");
     bool current = vshCommandOptBool(cmd, "current");
-    int niothreads = 0;
+    size_t niothreads = 0;
     virDomainIOThreadInfoPtr *info;
     size_t i;
     int maxcpu;
@@ -7539,6 +7539,7 @@ cmdIOThreadInfo(vshControl *ctl, const vshCmd *cmd)
     virshControlPtr priv = ctl->privData;
     vshTablePtr table = NULL;
     bool ret = false;
+    int rc;
 
     VSH_EXCLUSIVE_OPTIONS_VAR(current, live);
     VSH_EXCLUSIVE_OPTIONS_VAR(current, config);
@@ -7554,10 +7555,11 @@ cmdIOThreadInfo(vshControl *ctl, const vshCmd *cmd)
     if ((maxcpu = virshNodeGetCPUCount(priv->conn)) < 0)
         goto cleanup;
 
-    if ((niothreads = virDomainGetIOThreadInfo(dom, &info, flags)) < 0) {
+    if ((rc = virDomainGetIOThreadInfo(dom, &info, flags)) < 0) {
         vshError(ctl, _("Unable to get domain IOThreads information"));
         goto cleanup;
     }
+    niothreads = rc;
 
     if (niothreads == 0) {
         ret = true;