Fix bug when resulted in NXDOMAIN answers instead of NODATA.

check_for_local_domain() was broken due to new code matching F_*
bits in cache entries for DNSSEC. Because F_DNSKEY | F_DS is
used to match RRSIG entries, cache_find_by_name() insists on an exact match
of those bits. So adding F_DS to the bits that check_for_local_domain()
sends to cache_find_by_name() won't result in DS records as well
as the others, it results in only DS records. Add a new bit, F_NSIGMATCH
which suitably changes the behaviour of cache_find_by_name().
diff --git a/CHANGELOG b/CHANGELOG
index a499107..00f0480 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -31,6 +31,9 @@
 	    --conf-dir=/etc/dnsmasq.d,\*.conf
 	    will load all the files in /etc/dnsmasq.d which end in .conf
  
+            Fix bug when resulted in NXDOMAIN answers instead of NODATA in
+            some circumstances.
+	    
 
 version 2.71
             Subtle change to error handling to help DNSSEC validation