Remove SunOS LWP support

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

libraries/libldap_r/thr_lwp.c (SunOS LWP) has since 1999 (rev 1.5) said:
/* This implementation NEEDS WORK.   It currently does not compile */

I suggest we kill LWP support.  Has anyone tried to use it since 1999?

Note, configure --with-threads=lwp turns into either Solaris
threads (#define HAVE_THR) or SunOS LWP (#define HAVE_LWP).

-- 
Hallvard