AIX libstdc++ multilib broken

[David Edelsohn]

	I will be happy to help test fixes.  I do not understand what
could be different about AIX than any other target requiring multilib.
Again, I build with GNU Make and even specify

SHELL=/usr/gnu/bin/bash CONFIG_SHELL=/usr/gnu/bin/bash

to speed up configure, so the shell should be consistent with GNU/Linux
targets.  I just don't see how this could be unique.  If it is, then
obviously we need to investigate exactly what different order of
execution, timestamps, file stats, etc. occur.

David