Update for Intel-15.
Update for Intel 15.0
In preparation for GCC-5 and/or the deprecation of __GXX_EXPERIMENTAL_CXX0X__ refactor GCC configuration.
Update existing VC14 support with patches from https://svn.boost.org/trac/boost/ticket/10489
Apply patch from https://svn.boost.org/trac/boost/ticket/5315.
Allows auto-linking code to synch up with Boost.Build with the --buildid option.
Only include <utility> when we absolutely have to as it's not so lightweight in C++11.  See https://github.com/boostorg/config/pull/40
Disable log1p and expm1 support in mingw - they often crash for reasons yet to be determined.
Fix typo, see https://svn.boost.org/trac/boost/ticket/10590
Reorganise library version detection, adds tentative fix for clang with libstdc++.  See issues 10600 and 7473
Reorganize clang config to avoid macro redefinitions and fix GCC-4.8, 4.9, and 5.0 detection.
Enable <thread> for gcc-4.8 and later.
Disable thread support headers depending on values of internal libstdc++ macros.
Rework Intel config to make it both more accurate in C++11 mode (hopefully!) and easier to maintain.
Disable __int128 support when the compiler is really CUDA.
See https://svn.boost.org/trac/boost/ticket/10418.
Merge branch 'develop' of https://github.com/boostorg/config into develop
Add helper macro - BOOST_ATTRIBUTE_UNUSED - to suppress unused type/variable warnings.
Doc regen.
Add C++14 support based on https://github.com/boostorg/config/pull/39
Fix spelling of one C++14 macro, improve C++14 auto-detection.
Fix broken <atomic> with clang, tentatively fix clang number separator option.
Improve GCC C++14 feature detection.