I think between us, Michael Hitch and I have figured out what's going
wrong in ld.so.  No estimate yet on when it'll be fixed, though.

If it's as simple as updating the ld.so binary I'll consider shipping
an updated binary with 1.3.1, or at least as a replacement.

In the meantime, I've put a tarfile with copy of Dan's relinked twm
in  ftp://ftp.netbsd.org/pub/NetBSD/arch/pmax/gnumalloc-fix/x11.tgz.
Use at your own risk, etc.