[Bro] Add a new protocol

[nicolas.retrain at cea.fr]

Hi

I need to detect protocols which are not support in bro yet, so I am 
considering adding them into Bro.
However I am stuck at the beginning, I can't found where or how are 
declared all files.h into CMake (so compile with my news files fails 
because .o aren't generated).

Also, if you have some good articles or advices which could help me in 
adding protocols, it would be nice.
Thanks for your help.

Regards,

Nicolas