Merge from develop

Inheriting std::iterator is deprecated in c++17.

Avoid advancing null pointers, which is UB

* When  __BORLANDC__ and __clang__ are defined we have clang-based compilers from Embarcadero, which take after clang and not bcc32.

* Test fixes when wide character regex is turned off.

Advancing a null pointer by a distance other than 0 is UB in C++20
(7.6.6 Additive operators [expr.add]/4).

This issue is reported by clang 10 UBSan here:

https://travis-ci.org/github/boostorg/log/jobs/683550541#L1204

VxWorks support

Therefore get rid of all of that and replace inheritance by lifting std::iterator's members into the derived class.

Signed-off-by: Daniela Engert <dani@ngrt.de>

Removed executable attribute from files.

VxWorks uses same definitions as QNX, so with this change all tests passed

Replace deprected/removed C++98 function adapters by inline type defi…

Signed-off-by: Daniela Engert <dani@ngrt.de>

Create metadata file.

Fix variable aliasing warnings

MSVC 14 has new variable shadowing warnings, which are on by default and spam the Boost regression test output:
"warning C4456: declaration of '...' hides previous local declaration".
This renames a few variables to make MSVC happy.

Drop unused typedef in boost::xpressive::detail::make_assert_word

Conflicts:
	include/boost/xpressive/detail/core/adaptor.hpp
	include/boost/xpressive/detail/core/list.hpp

[SVN r86268]

[SVN r86267]

Process #ifdef...#endif blocks.

[SVN r86243]

[SVN r86123]

 git grep -h -B1 "^#\s*pragma once" | grep -v pragma | sort | uniq

is now clean.

[SVN r85952]

merge [85118],[85119],[85120],[85121] from trunk; fixes #8843, fixes #8880, fixes #8882, fixes #8474

[SVN r85427]

[SVN r85121]