[boost] lockfree workaround for msvc compiler bug (was Re: Boost 1.61.0 Release Candidate 2)

Subject: [boost] lockfree workaround for msvc compiler bug (was Re: Boost 1.61.0 Release Candidate 2)
From: Tim Blechmann (tim_at_[hidden])
Date: 2016-05-11 02:51:32

> The second release candidates for the 1.61.0 release are now available at:

might be too late for 1.61, but since msvc's update fixed one compiler
bug by introducing another, boost.lockfree won't compile with the latest
msvc update.

the least intrusive change i could come up with is the following:

https://github.com/boostorg/lockfree/commit/547f131cb0034ea9d8fe5de33911730cf2bd294a

it doesn't introduce any functional change, but gives users the
possibility to force the use of boost::atomic instead of relying on
std::atomic by defining the BOOST_LOCKFREE_FORCE_BOOST_ATOMIC macro.

is it ok to merge this into master before 1.61 comes out? we could add a
release note:

--
Due to a bug in VS 2015 Update 2 boost.lockfree might trigger error
C2338. The suggested workaround is to define
BOOST_LOCKFREE_FORCE_BOOST_ATOMIC.
--
cheers,
tim