BUG/MEDIUM: arg: ensure that we properly unlink unresolved arguments on error

BUG/MEDIUM: arg: ensure that we properly unlink unresolved arguments on error

If make_arg_list() fails to process an argument after having queued an
unresolvable one, it frees the allocated argument list but doesn't remove
the referenced args from the arg list. This causes a use after free or a
double free if the same location was reused, during the deinit phase upon
exit after reporting the error.

Since it's not easy to properly unlinked all elements, we only release the
args block if none of them was queued in the list.