gcc8 not compiling pkgsrc boost-libs-1.71.0

[Frank Kardel <kardel%netbsd.org@localhost>]

When bulk building pkgsrc boost libs 1.71.0 fails to compile with:

In file included from /usr/include/stddef.h:37,
                 from /usr/include/g++/cstddef:50,
                 from ./boost/config/compiler/gcc.hpp:165,
                 from ./boost/config.hpp:39,
                 from ./boost/log/detail/config.hpp:34,
                 from libs/log/src/syslog_backend.cpp:18:
./boost/asio/detail/impl/kqueue_reactor.ipp: In constructor 
'boost::asio::detail::kqueue_reactor::kqueue_reactor(boost::asio::execution_context&)':
./boost/asio/detail/impl/kqueue_reactor.ipp:32:5: error: invalid 
static_cast from type 'intptr_t' {aka 'long int'} to type 'void*'
     EV_SET(ev, ident, filt, flags, fflags, data, \
     ^~~~~~
./boost/asio/detail/impl/kqueue_reactor.ipp:54:3: note: in expansion of 
macro 'BOOST_ASIO_KQUEUE_EV_SET'
   BOOST_ASIO_KQUEUE_EV_SET(&events[0], interrupter_.read_descriptor(),
   ^~~~~~~~~~~~~~~~~~~~~~~~

Is gcc8 wrong or do we have a bug in boost-libs ?

Needless to say that this obstacle breaks over 600 packages...

Frank