perf tools: Use eprintf for pr_{err,warning,info} too

perf tools: Use eprintf for pr_{err,warning,info} too

Just like we do for pr_debug, so that we can have a single point
where to redirect to the currently used output system, be it
stdio or newt.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1268349164-5822-3-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>