* sysdeps/mach/hurd/bits/libc-lock.h: New file, initially copied from

* sysdeps/mach/hurd/bits/libc-lock.h: New file, initially copied from

	sysdeps/mach version.  Implement counting ("recursive") mutexes
	on top of cthreads mutexes.
	* sysdeps/mach/hurd/bits/stdio-lock.h: File removed; generic now works.

	* sysdeps/generic/bits/stdio-lock.h (_IO_lock_initializer): Define to
	_LIBC_LOCK_RECURSIVE_INITIALIZER if defined, else do an #error.
	(__libc_cleanup_region_start, __libc_cleanup_region_end,
	__libc_clean_end): Define these to call the cleanup function after
	normal exit when they're supposed to.

	* sysdeps/mach/bits/libc-lock.h (__libc_cleanup_region_start):
	Take new first arg DOIT, a boolean saying whether to really install
	any cleanup handler.
	(__libc_cleanup_region_end): Do nothing if start's DOIT arg was zero.
	(__libc_cleanup_end): Likewise.
	* stdio-common/vfscanf.c (LOCK_STREAM): Pass new arg.
	* stdio-common/vfprintf.c (buffered_vfprintf, vfprintf): Likewise.
	* sysdeps/mach/hurd/bits/stdio-lock.h (_IO_cleanup_region_start):
	Likewise.
	* misc/syslog.c (vsyslog, openlog, closelog): Likewise.
	* sysdeps/generic/bits/stdio-lock.h
	(_IO_cleanup_region_start, _IO_cleanup_region_start_noarg): Likewise.