perf callchain: Move validate_callchain to callchain lib

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --cc tools/perf/builtin-report.c
Simple merge

diff --cc tools/perf/util/callchain.c
Simple merge

diff --cc tools/perf/util/callchain.h
Simple merge