Slimmed down HP-UX native code

[Mark Kettenis]

Still worried about having to maintain too much code ;-) ?

$ cat hppah-nat.c infttrace.c | wc -l
    6996

$ cat hppa-hpux-nat.c inf-ttrace.c | wc -l
    1212

To be honest, the new code doesn't do follow-exec/fork/vfork.  But I
think I can implement that in less than 5000 lines of code ;-)

Mark