Detect Mac Os version and allow process-shared synchronization primitives when minimum target is Mac Os Lion or newer (refs #6108).
Remove boost/thread dependency in tests.
Interprocess: Remove obsolete MSVC version check
Remove obsolete MSVC check from pragma guard

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

is now clean.
Changed #include <boost/type_traits.hpp> with <boost/type_traits/alignment_of.hpp> + <boost/type_traits/make_unsigned.hpp> to avoid unnecessary header includes.
Notify all waiting threads in destructor to allow POSIX semantics on condition variables destruction.
Don't use EAGAIN as it's not used and requires missing cerrno
Fixed typo in release notes for 1.55
Fixed typo in release notes for 1.55 (again)