Add a _REENT_ERRNO() macro to encapsulate the access to the
_errno member of struct reent. This will help to replace the
structure member with a thread-local storage object in a follow
up patch.
Replace uses of __errno_r() with _REENT_ERRNO(). Keep __errno_r() macro for
potential users outside of Newlib.
* libc/include/sys/_types.h: Define _ssize_t as int if int is
32-bits, otherwise define it as long.
* libc/include/sys/types.h: Include <_ansi.h> and <sys/_types.h>
and define ssize_t as _ssize_t.
* libc/reent/readr.c: Change return type to _ssize_t.
* libc/reent/writer.c: Ditto.
* libc/sys/linux/Makefile.am: Add aio.c.
* libc/sys/linux/Makefile.in: Regenerated.
* libc/sys/linux/aio.c: New file.
* libc/sys/linux/sys/cdefs.h: Add __restrict_arr definition.
* libm/common/fdlibm.h: Undef __P before defining it.