perf tools: Move threads & last_match to threads.c

This was just being copy'n'pasted all over.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091013141629.GD21809@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>