* 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.