This patch implements native to Windows subset of pthreads API used by Git.
It allows to remove Pthreads for Win32 dependency for MSVC, msysgit and
Cygwin.
[J6t: If the MinGW build was built as part of the msysgit build
environment, then threading was already enabled because the
pthreads-win32 package is available in msysgit. With this patch, we can now
enable threaded code unconditionally.]
Signed-off-by: Andrzej K. Haczewski <ahaczewski@gmail.com> Signed-off-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>