It shouldn't build on any platform ( 'fold_constants' isn't exported anywhere)

I have to admit that my understanding of this is weak, but I believe that only some platforms require explicitly listing what symbols are publicly exported from a dynamic library. This is handled by makedef.pl in the perl source; from the comments there, this seems to be limited to Win32, wince, os2, AIX, netware, and MacOS. So problems like this (a module using a symbol that isn't available everywhere) do fairly regularly crop up. I think the fix is to add Perl_fold_constants to global.sym (by changing it to public in embed.fnc and running embed.pl) and rebuild perl :(.