rpc: correctly process sasl whitelist globs

Detected by Coverity.  We want to compare the result of fnmatch 'rv',
not our pre-set return value 'ret'.

* src/rpc/virnetsaslcontext.c (virNetSASLContextCheckIdentity):
Check correct variable.

src/rpc/virnetsaslcontext.c

@@ -132,7 +132,7 @@ int virNetSASLContextCheckIdentity(virNetSASLContextPtr ctxt,
             ret = 1;
             goto cleanup; /* Succesful match */
         }
-        if (ret != FNM_NOMATCH) {
+        if (rv != FNM_NOMATCH) {
             virNetError(VIR_ERR_INTERNAL_ERROR,
                         _("Malformed TLS whitelist regular expression '%s'"),
                         *wildcards);