[boost] [build] b2 headers don't work for sublibs

Subject: [boost] [build] b2 headers don't work for sublibs
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2014-08-30 13:09:01

Hi,

I'm trying to move some headers of Boost.MPL to a sublib Boost.MPL.Core. I've 
reorganized the repository as follows:

libs
  mpl
    book
    core
      include
        boost <- here and below are core headers
      test
      index.html
    doc
    example
    include
      boost <- here and below are the rest headers
    meta
    preprocessed
    test
    .git
    .gitattributes
    README.md
    index.html
    sublibs

The problem is when I run 'b2 headers' the command creates a symlink boost/mpl 
pointing to libs/mpl/include/boost/mpl, which leaves out all headers from 
libs/mpl/core/include/boost/mpl. How do I instruct Boost.Build to create links 
to the core headers?