boost: Bug-fix release

boost: Bug-fix release

This release fixes the following issues
[1] - A second run to build Boost was executed, even though
       Boost.Python3 was not selected.
[2] - Because wserialization and coroutine2 targets were removed from
       Boost building system, the flags "--without-wserialization" and
       "--without-coroutine2" no longer work and are now suppressed.
       The option coroutine2 just selects the necessary dependencies for
       the header-library to work.
       The sub-package wserialization just selects the serialization
       dependency and packs the wserialization shared object.

[1]: https://github.com/openwrt/packages/commit/cf67f5f47a7420049cd161a76eeb74f3a54ba219#comments
[2]: https://github.com/openwrt/packages/issues/4974

Signed-off-by: Carlos Miguel Ferreira <carlosmf.pt@gmail.com>