man-pages-3.57 is released

I've released man-pages-3.57. The release tarball is available on kernel.org. The browsable online pages can be found on man7.org. The Git repository for man-pages is available on kernel.org.

Among the more notable changes in man-pages-3.57 are the following:

• The open(2) manual page adds documentation of the O_TMPFILE flag, which provides a race-free method of creating unnamed temporary files. Such temporary files can, if desired, later be linked into the filesystem using linkat(2), after  being populated and adjusted to have to have the desired filesystem attributes (ownership, permissions, etc.). Thanks to Andy Lutomirski for providing the basis for that documentation.
• Vince weaver continues doing good work updating the perf_event_open(2) manual page, this time adding (with the help of Andi Kleen) documentation of the PERF_SAMPLE_TRANSACTION operation added in Linux 3.13.
• Andrey Vagin added documentation of the PTRACE_PEEKSIGINFO, PTRACE_GETSIGMASK, and PTRACE_SETSIGMASK operations to the ptrace(2) manual page.
• Eliezer Tamir added documentation of the SO_BUSY_POLL socket option to the socket(7) manual page.
• I added documentation of the TCP_USER_TIMEOUT and TCP_CONGESTION socket options to the tcp(7) manual page.
• Peng Haitao continued adding notes on thread-safety to various manual pages.

In addition, smaller improvements and fixes have been made to many other pages.