Pass down the tgid to userspace in u{stack,sym,mod,addr}().

Pass down the tgid to userspace in u{stack,sym,mod,addr}().

Userspace does not know how to attach to threads, only processes (thread group
leaders).  All it's doing after attaching is looking up symbols, which are per-
process anyway, so rather than go to the effort of teaching userspace to grab
and release non-thread-group-leaders, simply pass the tgid to userspace so that
it can grab everything the same way.

Also pass the pid (== tid) down, because DTrace consumers could reasonably want
to know the actual thread ID in which the u*() fired (though our userspace does
not care).

This means we are passing one extra item on the buffer for ustack() et al:
internal uses are adjusted accordingly.

Orabug: 18412802
Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>
Acked-by: Chuck Anderson <chuck.anderson@oracle.com>