Add missing #undef N to constructor.hpp.
Add missing #undef N to constructor.hpp.

luabind/luabind,davidar/luabind,decimad/luabind-deboostified,grafi-tt/luabind,Kazade/luabind-deboostified,luabind/luabind,MrApplejuice/luabind,lonski/luabind,alex85k/luabind,luabind/luabind,mapbox/luabind,luabind/luabind,alex85k/luabind,mdave88/luabind,rpavlik/luabind,plsytj/luabind,rpavlik/luabind,Wohlhabend-Networks/luabind-deboostified,rpavlik/luabind,Oberon00/luabind,galek/luabind-deboostified,Oberon00/luabind,rpavlik/luabind,alex85k/luabind,ltjax/luabind-deboostified,rpavlik/luabind,alex85k/luabind