perf tools: Factorize the dprintf definition

We have two users of dprintf: report and annotate. Another one
is coming with perf trace. Then factorize it into the debug
file.

While at it, rename dprintf() to dump_printf() so that it
doesn't conflicts with its libc homograph.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1250443461-28130-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>