Remove _IO_MTSAFE_IO from public headers.zack/testsuite-isomac-prep

_IO_MTSAFE_IO controls whether stdio is *built* with support for
multithreading.  In the distant past it might also have worked as a
feature selection macro, allowing library *users* to select
thread-safe or lock-free stdio at application build time, I haven't
done the archaeology.  Nowadays, defining _IO_MTSAFE_IO while using
the installed headers, or in _ISOMAC mode, will cause libio.h to throw
syntax errors.

This patch removes _IO_MTSAFE_IO from the public headers
(specifically, from libio/libio.h).  The internal-use-only macros
whose definitions were conditional on _IO_MTSAFE_IO are moved to
include/libio.h.  The other thing it controls is whether libio.h
defines _IO_lock_t itself or expects stdio-lock.h to have done it, and
we do still need a inter-header communication macro for that, because
stdio-lock.h can only define _IO_lock_t as a typedef.  I've invented
_IO_lock_t_defined, which is defined by both versions of stdio-lock.h.

I suspect that this entire mechanism is vestigial, and that glibc
won't build anymore if you *don't* define _IO_MTSAFE_IO, but that's
another patchset.  The bulk of libio.h is internal-use-only stuff that
no longer makes sense to expose (libstdc++ gave up on making a FILE
the same object as a C++ filebuf *decades* ago) but that, too, is
another patchset.

	* libio/libio.h: Condition dummy definition of _IO_lock_t on
	_IO_lock_t_defined, not _IO_MTSAFE_IO.	Move macro definitions
	conditioned on _IO_MTSAFE_IO ...
	* include/libio.h: ... here.

	* sysdeps/generic/stdio-lock.h, sysdeps/nptl/stdio-lock.h:
	Define _IO_lock_t_defined after defining _IO_lock_t.

0 files changed, 0 insertions, 0 deletions