cannot dlopen non loadable libpthread error

[Mayuresh <mayuresh%acm.org@localhost>]

When running sane-backend (more precisely, when running scanimage in DEBUG
mode) I get the following error

[dll] load: dlopen() failed (Cannot dlopen non-loadable
/usr/lib/libpthread.so.1)

I am on NetBSD 6.0 RC1 on i386.

The said program does not link with libpthread. (ldd doesn't show that.)
It tries to open libpthread dynamically with dlopen.

Additional observation:
sane-backends Makefile includes the following (and I don't know whether to
relate this information to above problem)
../../mk/pthread.buildlink3.mk

There is an old thread with this subject, which did not help in this case:
http://mail-index.netbsd.org/pkgsrc-users/2012/02/21/msg015711.html

Would appreciate some inputs.

Mayuresh