tvbuff composite: fix Dereference of null pointer found by Clang Analyzer

Change-Id: Ia43cb2e1cab99e4b769c8dfa0805d8e38e225a1c
Reviewed-on: https://code.wireshark.org/review/3990
Reviewed-by: Evan Huus <eapache@gmail.com>
tvbuff composite: add modelines infos (tabs)

Change-Id: I9ea2160b550243b45f6798ad3339f6a45b34a4ef
Reviewed-on: https://code.wireshark.org/review/3991
Reviewed-by: Evan Huus <eapache@gmail.com>