Currently, on AIX, whenever the -j option is passed to make there are many WARNINGS from the loader (ld) re: duplicate symbols.

While it is not possible to eliminate these warnings completely - as some are not related to the Python build, but external (3rd party) packaging - MOST of these warnings can be eliminated by ensuring that the export file creation completes before additional steps try to use it.

By adding a small test to see if the export file is in the process of being made - and waiting for that to finish - the messages "go away".

The PR that is being proposed only affects AIX (a script named makeaix_exp). The script has not been modified in 22 years - so I guess the -j option is something that showed up after 1998 :)

I know it is not perfect - but removes a tremendous amount of noise - most of the time.

Michael

p.s. requesting backport to 3.8 so all buildbots benefit.