[boost] [iostreams] building zlib from source

I am working on improving detection of external dependencies (for 1.42), and I've noticed that the iostreams library is rather smart when it comes to building zlib (and bz2). It allows the user to specify either: - location of headers and libraries files, or - location of sources for zlib In the latter case, the sources will be compiled automatically. How important is the second use case? It's not very hard to support, and appears handy for Windows users, but if in practice, nobody cares, I can spend the time on other matters. Thanks, Volodya