perf hist: Fix missing getline declaration

hist.c needs to include util.h so that it gets stdio.h
inclusion with __GNU_SOURCE defined.

Fixes:
	util/hist.c: In function ‘hist_entry__parse_objdump_line’:
	util/hist.c:931: erreur: implicit declaration of function ‘getline’
	util/hist.c:931: erreur: nested extern declaration of ‘getline’

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1273772836-11533-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>