perf tools: Fix build on older systems

In RHEL 6.7:

  CC       /tmp/build/perf/util/parse-events.o
  cc1: warnings being treated as errors
  util/parse-events.c: In function ‘parse_events_add_cache’:
  util/parse-events.c:366: error: declaration of ‘error’ shadows a global declaration
  util/util.h:136: error: shadowed declaration is here

Rename it to 'err'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 43d0b978 ("perf tools: Enable config and setting names for legacy cache events")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -363,7 +363,7 @@ static int config_attr(struct perf_event_attr *attr,
 
 int parse_events_add_cache(struct list_head *list, int *idx,
 			   char *type, char *op_result1, char *op_result2,
-			   struct parse_events_error *error,
+			   struct parse_events_error *err,
 			   struct list_head *head_config)
 {
 	struct perf_event_attr attr;
@@ -425,7 +425,7 @@ int parse_events_add_cache(struct list_head *list, int *idx,
 	attr.type = PERF_TYPE_HW_CACHE;
 
 	if (head_config) {
-		if (config_attr(&attr, head_config, error,
+		if (config_attr(&attr, head_config, err,
 				config_term_common))
 			return -EINVAL;