perf stat: Add noise output for csv mode

Previously, when you want perf-stat to output the statistics in
csv mode, no information of the noise will be printed out.

For example right now we output this --repeat information:

 ./perf stat -r3 -x, sleep 1
 1.164789,task-clock
 8,context-switches
 0,CPU-migrations
 219,page-faults
 3337800,cycles

With this patch, the output will be appended with an additional
entry for the noise value:

 ./perf stat -r3 -x, sleep 1
 1.164789,task-clock,3.75%
 8,context-switches,75.00%
 0,CPU-migrations,100.00%
 219,page-faults,0.00%
 3337800,cycles,3.36%
Signed-off-by: Zhengyu He <zhengyuh@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Stephane Eranian <eranian@google.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1308861942-4945-1-git-send-email-zhengyuh@google.comSigned-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-stat.c

@@ -517,6 +517,9 @@ static void print_noise_pct(double total, double avg)
 	if (avg)
 		pct = 100.0*total/avg;
 
+	if (csv_output)
+		fprintf(stderr, "%s%.2f%%", csv_sep, pct);
+	else
 		fprintf(stderr, "  ( +-%6.2f%% )", pct);
 }
 
@@ -882,13 +885,13 @@ static void print_counter_aggr(struct perf_evsel *counter)
 	else
 		abs_printout(-1, counter, avg);
 
+	print_noise(counter, avg);
+
 	if (csv_output) {
 		fputc('\n', stderr);
 		return;
 	}
 
-	print_noise(counter, avg);
-
 	if (scaled) {
 		double avg_enabled, avg_running;