linking against pthread for a shared library

[Rong-en Fan]

miwi@ and I are working on solving
an issue with devel/upnp and misc/ushare
problem. Essentially, the problem is that
devel/upnp builds a shared library called
libthreadutil.so which uses threading library.
misc/ushare is a consumer of that library.

On 7.x system, if you ldd on libthreadutil.so
(this is i386)

./work/libupnp-1.6.0/threadutil/.libs/libthreadutil.so:
        liblwres.so.30 => /usr/lib/liblwres.so.30 (0x2817d000)
        libc.so.7 => /lib/libc.so.7 (0x2807e000)
        libthr.so.3 => /lib/libthr.so.3 (0x2818d000)

But on 6.x and 5.x, you only get (this is amd64)

./work/libupnp-1.6.0/threadutil/.libs/libthreadutil.so:
        liblwres.so.10 => /usr/lib/liblwres.so.10 (0x800941000)

So, one needs to pass -pthread when using
libthreadutil.so. In my understanding, the behavior
on 7.x is more correct (or reasonable).

Any ideas how to solve this problem?

Regards,
Rong-En Fan