Instead of failing with ENAMETOOLONG, which is swallowed by
pthread_set_name_np() anyway, truncate the given name to MAXCOMLEN+1
bytes. This is more likely what the user wants, and saves the
caller from truncating it before the call (which was the only
recourse).
Polish pthread_set_name_np(3) and add a .Xr to thr_set_name(2)
so the user might find the documentation for this behavior.
Reviewed by: jilles
MFC after: 3 days
Sponsored by: Dell EMC
Add text to thr_exit(2) and thr_new(2) discouraging their use in
applications since calling these in a process with libthr loaded will
confuse libthr and is likely to cause hangs or crashes.
The thr_kill2(2) call is not used by libthr and may be useful in special
applications.
The other calls can be used in applications but it should not be necessary.
