* dtable.h (dtable::lock): Make static.
	Introduce _STDIO_BSD_SEMANTICS flag to switch fclose/exit file flushing
	semantics from POSIX to BSD.
	* libc/stdio/fclose.c (_fclose_r): Conditionalize file flushing on
	_STDIO_BSD_SEMANTICS.  Call __sflush_r rather than _fflush_r.  Add
	comment.
	* libc/stdio/fflush.c (__sflushw_r): New function, only available
	if _STDIO_BSD_SEMANTICS is defined.
	* libc/stdio/findfp.c (_cleanup_r): Call _fwalk_reent rather than
	_fwalk.  Conditionalize cleanup function call on _STDIO_BSD_SEMANTICS.
	Add comments.  Add FIXME.
	* libc/stdio/local.h (__sflushw_r): Declare if _STDIO_BSD_SEMANTICS is
	defined.
	* include/cygwin/config.h (_STDIO_BSD_SEMANTICS): Define as 1.
	* libc/include/sys/_default_fcntl.h (LOCK_SH): Define.
	(LOCK_EX): Likewise.
	(LOCK_NB): Likewise.
	(LOCK_UN): Likewise.
	(flock): Declare.
	* include/sys/file.h (LOCK_SH): Drop definition in favor of new
	definitions in newlib.
	(LOCK_EX): Ditto.
	(LOCK_NB): Ditto.
	(LOCK_UN): Ditto.
	(flock): Ditto.
	(F_OK): Drop.  Already correctly defined in unistd.h.
	(X_OK): Ditto.
	(W_OK): Ditto.
	(R_OK): Ditto.
	* syscalls.cc (popen): Introduce Glibc 'e' flag to allow thread-safe
	opening of the pipe with O_CLOEXEC flag.  Simplify FD_CLOEXEC handling.
*** empty log message ***
	* passwd.cc (setpassent): Align to BSD definition.
	* libc/include/pwd.h: Use __foo_VISIBLE macros from sys/cdefs.h.
	(setpassent): Declare.
* dtable.h (dtable::lock): Revert static.
(dtable::unlock): Ditto.
	* include/netinet/ip6.h: New file, copied from FreeBSD vebatim.
	* libc/include/setjmp.h (longjmp): Mark "noreturn" when building with
	GCC.