David, I will take the "thank you for restoring bootstrap for AIX" as implied in your e-mail.
Second, the patch that you applied is unacceptable. ASYNC_IO already is set to zero for AIX.
There is a clear procedure for this something that you deem "unacceptable": Submit a patch (for which I promise a fast review) or, if you feel that the patch is simple and obvious, commit it yourself and announce it to the fortran and gcc-patches mailing list. Thomas