Improve AIX port.

Improve AIX port.

This doesn't fix the bug, but it makes progress: Emacs builds now.
* unexaix.c: Include inttypes.h, stdarg.h.
(report_error, report_error_1): Mark as _Noreturn.
(report_error): Don't report the wrong errno.
(report_error_1): Now varargs.  All callers changed.
(make_hdr): Use uintptr_t, not unsigned, when converting pointers
to unsigned.  Don't use ADDR_CORRECT, as it no longer exists.
(write_ptr): Use %p to print address rather than %lx and a cast
to unsigned long.  Grow buffer a bit, to be safer.