[lwres] Fix (32 bit ?) MSVC-2015 warning: "conversion from 'size_t' to 'guint16', possible loss of data"

Change-Id: Ifc71d1c2afc3ff16f950f2f1c3c9e7142d62fc16
Reviewed-on: https://code.wireshark.org/review/10007
Reviewed-by: Bill Meier <wmeier@newsguy.com>

epan/dissectors/packet-lwres.c

@@ -200,7 +200,7 @@ static const value_string message_types_values[] = {
 static void dissect_getnamebyaddr_request(tvbuff_t* tvb, proto_tree* lwres_tree)
 {
     guint32 flags,family;
-    guint16 addrlen, slen;
+    guint   addrlen, slen;
     const char* addrs;
 
     proto_tree* nba_request_tree;