This replaces boost::thread and most mutexes and condition variables with
std equivalents. It also adds support for std lock types to the strictest_lock
type trait.
This significantly, although not completely, reduces the dependency on
Boost.Thread.
Refs https://github.com/boostorg/log/issues/232.
The _SCL_SECURE_NO_WARNINGS, _SCL_SECURE_NO_DEPRECATE,
_CRT_SECURE_NO_WARNINGS and _CRT_SECURE_NO_DEPRECATE macros need to be
defined for every compiler that uses MSVC C/C++ runtime, so instead of
duplicating these definitions in multiple places, define them for
Windows platform regardless of the compiler. In particular, they are
now defined for clang-cl.
The default filter/formatter factories will now be able to extract severity
level values of type boost::log::trivial::severity_level. For filters, this
is only supported for attributes with the "Severity" name.
Some tests pull in pthread rwlock and therefore need _XOPEN_SOURCE=600
or higher to compile. Added platform defines to tests and examples
for good measure.
For MinGW worked around Boost.Build error when BOOST_LOG_WITHOUT_EVENT_LOG
is defined.
