clang scan-build warnings

clang scan-build reported two warnings in commit 7c210a2b. In summary:

lib/dns/client.c, line 2903:

2901	if (zonename != NULL) {
2902		uctx->zonename = dns_fixedname_name(&uctx->zonefname);
2903		result = dns_name_copy(zonename, uctx->zonename, NULL);
2904	}

The value of "result" set at line 2903 is never read.

bin/named/config.c, line 838

829		newsize = i * sizeof(isc_dscp_t);
830		oldsize = dscpcount * sizeof(isc_dscp_t);
831		if (i != 0) {
832			tmp = isc_mem_get(mctx, newsize);
833			memmove(tmp, dscps, newsize);
834		} else
835			tmp = NULL;
836		isc_mem_put(mctx, dscps, oldsize);
837		dscps = tmp;
838		dscpcount = i;

The value of "dscpcount" set at line 838 is never read.

Full details in https://jenkins.isc.org/view/BIND/job/bind9-clang-static-analyzer/431/clangScanBuildBugs/