perf config: Check not only section->from_system_config but also item's

Currently section->from_system_config is being checked multiple times.
item->from_system_config should be checked instead, when iterating thru
the items in a section. Fix it.

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1504754325-9724-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-config.c

@@ -59,7 +59,7 @@ static int set_config(struct perf_config_set *set, const char *file_name,
 		fprintf(fp, "[%s]\n", section->name);
 
 		perf_config_items__for_each_entry(&section->items, item) {
-			if (!use_system_config && section->from_system_config)
+			if (!use_system_config && item->from_system_config)
 				continue;
 			if (item->value)
 				fprintf(fp, "\t%s = %s\n",