[boost] [fiber] Boost.Fiber 1.63.0 RC1 tries to use std::mutex which MinGW doesn't have

Subject: [boost] [fiber] Boost.Fiber 1.63.0 RC1 tries to use std::mutex which MinGW doesn't have
From: Stephan T. Lavavej (stl_at_[hidden])
Date: 2016-12-13 01:37:42

In both 1.62.0 and 1.63.0 RC1, building Boost.Fiber with my MinGW-w64 distro
fails. That's because libstdc++ doesn't natively support the Clause 30
multithreading headers (std::mutex etc.) on Windows, and I make no attempt
to build wrappers between the Windows and POSIX APIs (which is my personal
choice). Boost's build system should detect this, and use the perfectly
valid Boost.Thread implementation. Indeed, "C++11 mutex : no" is printed
during the build's configuration, but Fiber's build fails anyways.

My configuration output, and the errors emitted by a typical translation
unit, are recorded here:
https://github.com/StephanTLavavej/mingw-distro/issues/28

Thanks,
STL