JXTA: ask for one more segment, not one more byte

Otherwise we end up doing reassembly of long messages one painful byte at a time
even when all of those bytes are in the same TCP payload. This results in
ridiculous memory usage.

Change-Id: Ie28d5ade1fec54e6ebc225341582270651d7371c
Closes-Bug: 10018
Reviewed-on: https://code.wireshark.org/review/1312
Reviewed-by: Evan Huus <eapache@gmail.com>

epan/dissectors/packet-jxta.c

@@ -780,7 +780,7 @@ static int dissect_jxta_welcome(tvbuff_t * tvb, packet_info * pinfo, proto_tree
             return 0;
         } else {
             /* ask for more bytes */
-            return -1;
+            return -DESEGMENT_ONE_MORE_SEGMENT;
         }
     }