openposix/.../pthread_cond_timedwait: 2-2, 2-3

Fix rare segfaults.

The retval passed to pthread_join() is a pointer
to integer which is wrong as on 64 bit platform
sizeof(void*) == 8 while sizeof(int) == 4. The
pthread_exit() then rewrites part of the stack
of the main process which may cause segfault.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>