games/glob2: unbreak with boost 1.69
src/AIEcho.cpp:4390:9: error: no viable conversion from returned value of type 'boost::logic::tribool' to function return type 'bool'
return is_end!=rhs.is_end || team!=rhs.team || building_type!=rhs.building_type || level!=rhs.level || construction_site!=rhs.construction_site;
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~PR: 232525