improved thread id reporting

[Eli Zaretskii]

> Date: Sun, 5 Apr 2009 13:36:06 -0700
> From: Doug Evans <dje@google.com>
> 
> [Switching from thread #1, Thread 0x2aaaab6b0f30 (LWP 14403)
>              to thread #2, Thread 0x40800960 (LWP 14406)]

Maybe

  [Switching from thread 1, ID 0x2aaaab6b0f30 (LWP 14403)
               to thread 2, ID 0x40800960 (LWP 14406)]

and

  [Thread 4, ID 0x41802960 (LWP 14408) exited]

is slightly better, as it solves issue 1).  As for 2), I personally
don't mind it too much.  But if we want a single line, I can suggest

  [Thread switch: #1 (ID 0x2aaaab6b0f30, LWP 14403) -> #2 (ID 0x40800960, LWP 14406)]