perf hists browser: Change print format from %lu to %PRIu64

The nr_events variable in tools/perf/ui/browsers/hists.c is of type u64,
so the print format (%lu) causes 'perf report' to show 0 event count
when running with 32-bit userspace without redirection.

This patch fixes that problem by printing nr_events as PRIu64.
Signed-off-by: Tom Huynh <tom.huynh@freescale.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: Matt Mullins <mmullins@mmlx.us>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1417541842-9747-1-git-send-email-tom.huynh@freescale.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/hists.c

@@ -1252,7 +1252,7 @@ static int hists__browser_title(struct hists *hists,
 
 	nr_samples = convert_unit(nr_samples, &unit);
 	printed = scnprintf(bf, size,
-			   "Samples: %lu%c of event '%s', Event count (approx.): %lu",
+			   "Samples: %lu%c of event '%s', Event count (approx.): %" PRIu64,
 			   nr_samples, unit, ev_name, nr_events);