We can't go very far with libio cleanups as long as we still have
_IO_MTSAFE_IO, and I am not tackling that in this patch series,
but we can at least make the maze of stdio-related headers a
little less complicated.
In this patch, libio.h moves back out of bits/ into the top level of
the libio subdirectory, and is merged with libio/bits/libio-ldbl.h
(which also used to be installed) and include/libio.h. Since almost
no files include libio.h directly, this is quite straightforward.
libio.h is now always used with _LIBC defined, so all of the _LIBC ||
_GLIBCPP_USE_WCHAR_T conditionals are unnecessary. Similarly, the
ifdef nest surrounding the definition of _IO_fwide_maybe_incompatible
can collapse down to a single SHLIB_COMPAT check. I also took the
opportunity to add some checks for configuration botches to libio.h.
Installed stripped libraries are unchanged by this patch.
* libio/bits/libio.h: Move back to libio/libio.h and adjust
multiple-include guard to match.
Merge contents of libio/bits/libio-ldbl.h and include/libio.h
into this file.
Remove preprocessor conditionals that are always true and/or
redundant to other preprocessor conditionals in the same nest.
Include shlib-compat.h unconditionally.
Error out if _LIBC is not defined, or if _ISOMAC is defined,
or if _IO_MTSAFE_IO is defined but _IO_lock_t_defined is not
defined after including stdio.h.
Use __BEGIN_DECLS/__END_DECLS.
* libio/bits/libio-ldbl.h, include/bits/libio.h: Delete file.
* include/stdio.h, libio/iolibio.h, libio/libioP.h: Include
libio.h as <libio/libio.h> rather than as <bits/libio.h>.