On Mac OS X deadline_timer::cancel() may hangs

[Andrew Kargalov <a.kargalov@…>]

When deadline_timer is canceled from signal handler after the next signal arrived it cause hang on detail::posix_mutex::lock().

This behaviour couldn't be reproduced on linux and freebsd.

[Andrew Kargalov <a.kargalov@…>]

minimal test case

[chris_kohlhoff]

(In [76427]) Fix deadlock on Mac OS X. Refs #6275.

[chris_kohlhoff]

(In [76516]) Merge from trunk:

• Chrono support.

• Added object_handle support.

• Need to enable the basic_handle class when object_handle is supported.

• Update copyright notices.

• Fix MSVC "performance warning".

• Fix for NetBSD. Fixes #6098.

• Fix regression in buffered_write_stream. Fixes #6310.

• Fix deadlock on Mac OS X. Fixes #6275.

• On linux, connect can return EAGAIN in certain circumstances. Remap to another error so that it doesn't look like a non-blocking operation. Fixes #6048.

• Fix non-paged pool "leak" on Windows when io_service is repeatedly run without anything to do. Fixes #6321.

• Disable object_handle on Windows CE.

• Add extra include required for OVERLAPPED struct.

• Fix doxygen comments.

• Update documentation.

• Add missing class.

• Update copyright year.