AIX buildfarm failure

I am seeing buildfarm failures on AIX because stdio.h is being included
before pg_config.h (which has the definition of _LARGE_FILES).

The problem is stemming from math.h including stdlib.h, which (after
several more inclusions) ends up including stdio.h.

This is where the fgetpos64 different definitions is coming from.

If I move <math.h> down after "postgres.h" in nodeHash.c, the problem
goes away.

Do we want to consider putting math.h into the standard include set?

Or is there a general rule that postgres.h needs to be the first include
file (before system headers, etc)?

Thanks,-rocco