UNRESOLVED: Bbc detector build broken - investigate

Bbc detector is not included in build and in current state, if we include it, then its build is broken anyway.
REASON: its CMakeLists contains FairRoot directories, which was never addressed when MPDroot was decoupled from FairRoot.

set(INCLUDE_DIRECTORIES
${CMAKE_SOURCE_DIR}/geobase 
${CMAKE_SOURCE_DIR}/parbase 
${CMAKE_SOURCE_DIR}/base 
${CMAKE_SOURCE_DIR}/mcstack 
${CMAKE_SOURCE_DIR}/fairtools
${CMAKE_SOURCE_DIR}/bbc
)

As bbc detector is not our responsibility, it is reasonable in the issue #54 (closed) to simply move bbc directory under new directory detectors (!347 (merged)).
It will make no difference for bbc group once they decide to include their detector in the build and fix its broken build.

If !347 (merged) is accepted, this issue can be closed and market as UNRESOLVED (as the build fix does not depend on us).