Thanks Isaiah. Indeed the symbol avma appears to not be exported, which is obviously nothing to do with Julia.
I had completely discounted this possibility, since Pari is used by other projects in precisely the same way we are using it. In fact, you can't do much of anything at all with the Pari library without manipulating avma. I have absolutely no idea how this issue can have gone unreported before. But I'll take it up with the Pari devs directly. Thanks for the quick suggestion. Bill.
