config: clang - detect support for int128

[SVN r86497]
Clang using VC++ RTL currently does not support char16_t or char32_t

[SVN r86675]
Suppress auto declarations for current Cray C++
Fix typo from https://github.com/boostorg/config/pull/2
Merge pull request #1 from rsdale/develop

Suppress auto declarations for current Cray C++
Apply patch from https://github.com/ahmedcharles/config/commit/62c63fc58ff17d49b2a2373e98201046f239ebd0
Merge branch 'develop' of https://github.com/boostorg/config into develop
For VC++ and clang-cl if _HAS_EXCEPTIONS is 0, then the <exception> header must be manually included before the <typeinfo> header to avoid compiler errors.
Merge branch 'develop' of https://github.com/boostorg/config into develop
Fix typo in macro name - should be BOOST_NO_ATOMIC_SMART_PTR.
Add BOOST_NO_CXX11_HRD_ATOMIC.
Regenerate docs.
See https://svn.boost.org/trac/boost/ticket/8929.
Merge branch 'develop' of https://github.com/boostorg/config into develop
GCC-4.7x at least on Mingw does not have a conforming <atomic> header - at least not that you can link to.
Reorganize WinCE config based on https://svn.boost.org/trac/boost/ticket/9095.
Fix for nvcc, see https://svn.boost.org/trac/boost/ticket/9392
Apply patch from https://svn.boost.org/trac/boost/ticket/9410
Fix buggy test cases.
VC++ has <atomic> in recent versions.
Add some const qualifiers in the hopes it will fix clang C++14 mode failures.
Fix two more typos.
Corrected spelling change in comment
Merge branch 'develop' of https://github.com/boostorg/config into develop