threads and HPUX 10

[Joseph H. Buehler]

Someone (gcc) reported problems under HPUX 10 that were related to
threads.  I had similar problems, compile failing with missing
pthread.h.

I believe that this is due to some lines recently added to the end of
gcc/config/pa/t-pa.  They appear to force multilib compilation with
threads, even when the right headers are not on the machine, and even
if I specify no threads when configuring.  I removed the lines from
t-pa and the problem appears to have gone away.

Joe Buehler