Boost.Predef still broken in 1.71 RC 1

From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2019-08-12 10:42:44

As reported earlier, Boost.Build's predefined macro testing support is
still misdetecting in RC 1:

Using Boost 1.71 RC 1 with VS2019:

b2 libs/outcome/test
Performing configuration checks

    - default address-model    : 32-bit
    - default architecture     : x86
    - !BOOST_COMP_GNUC         : no
    - BOOST_COMP_GNUC >= 6.0   : no
    - !BOOST_COMP_CLANG        : no
    - BOOST_COMP_CLANG >= 4.0  : no
    - Boost.Config Feature Check: cxx14_variable_templates : yes
    - Boost.Config Feature Check: cxx14_constexpr : yes
    - !BOOST_COMP_GNUC         : no
    - BOOST_COMP_GNUC >= 6.0   : no
    - !BOOST_COMP_CLANG        : no
    - BOOST_COMP_CLANG >= 4.0  : no
    - Boost.Config Feature Check: cxx14_variable_templates : yes
    - Boost.Config Feature Check: cxx14_constexpr : yes
...found 1 target...

Using Boost 1.71 RC 1 with GCC 7.3 on Linux:

g++ --version
g++ (Ubuntu 7.3.0-27ubuntu1~18.04) 7.3.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

./b2 libs/outcome/test
Performing configuration checks

    - !BOOST_COMP_GNUC         : no
    - BOOST_COMP_GNUC >= 6.0   : no
    - !BOOST_COMP_CLANG        : no
    - BOOST_COMP_CLANG >= 4.0  : no
    - default address-model    : 64-bit
    - default architecture     : x86
    - Boost.Config Feature Check: cxx14_variable_templates : yes
    - Boost.Config Feature Check: cxx14_constexpr : yes
    - !BOOST_COMP_GNUC         : no
    - BOOST_COMP_GNUC >= 6.0   : no
    - !BOOST_COMP_CLANG        : no
    - BOOST_COMP_CLANG >= 4.0  : no
    - Boost.Config Feature Check: cxx14_variable_templates : yes
    - Boost.Config Feature Check: cxx14_constexpr : yes
...found 1 target...