21.5 Mule build failure

[Stephen J. Turnbull]

Aidan Kehoe writes:
 > 
 >  Ar an dara lá de mí Deireadh Fómhair, scríobh Vin Shelton: 
 > 
 >  > I am also seeing this build failure on Windows, although neither of my
 >  > Ubuntu-based builds is failing.  Aidan (leaping to the conclusion that
 >  > one of your recent check-ins caused this) - do you have any insight
 >  > into what's going on?  What do you need from me to debug this?
 > 
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 > Am seeing it locally, so that?s unnecessary. 

Here's a WAG:  sizeof(various things) differs on 64-bit vs 32-bit
platforms, and we've changed how storage sizes are computed recently
when stuffing objects into opaques and the like.