inconsistent #defines

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

liblthread/stack.c defines get_stack and free_stack if defined(sunos4),
liblthread/thread.c and slurpd/tsleep.c use them if defined(HAVE_LWP).
I expect these conditionals should be the same, unless it means that
sunos4 has LWP but lacks get_stack/free_stack.

If you keep the `sunos4':
cc or gcc don't define sunos4.  I think you can try someting like
 (defined(sun) || defined(__sun__)) && !(defined(__SVR4) || defined(__svr4__).
sun & co are defined on both sunos4 and solaris, but only the latter
defines __SVR4 & co).

-- 
Hallvard