dlfcn symbols cast to void* breaks ast_evaluator

[bvdberg]

if using RTLD_NEXT (or other symbol there), it causes an assert:

ast/value.c2:754: function ast.Value.castAs: Assertion failed: qt.isBuiltin()

can be triggered by 'c2c c2c -i'

[chqrlie]

I have a fix for this but I cannot reproduce the bug, can you provide offending code?

[bvdberg]

on master branch: c2c c2c -i