perf timechart: Fix the wakeup-arrows that point to non-visible processes

The timechart wakeup arrows currently show no process
information when the waker/wakee are processes that are not
actually chosen to be shown on the timechart.

This patch fixes this oversight, by looking through all
processes (after giving preference to visible processes) as well
as falling back to just showing the PID if no name for the
process can be resolved.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091020064649.0e4959b2@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>