perf events parse: Use just one parse events state struct

Andi reported problems when parse errors were detected with vendor
events (json), because in the yyparse/parse_events_parse function we
dereferenced the _data parameter to two different structs, with
different layouts, which ended up making parse_events_evlist->error to
point to random stack addresses.

Fix it by making _data to always be struct parse_events_state, changing
the only place where 'struct parse_events_term' was used in
parse_events.y.
Reported-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bc27lshz823hxl8n9nkelcgh@git.kernel.org
Fixes: 90e2b22d ("perf/tool: Add support to reuse event grammar to parse out terms")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -1656,7 +1656,7 @@ static int parse_events__scanner(const char *str, void *data, int start_token)
  */
 int parse_events_terms(struct list_head *terms, const char *str)
 {
-	struct parse_events_terms data = {
+	struct parse_events_state data = {
 		.terms = NULL,
 	};
 	int ret;

tools/perf/util/parse-events.h

@@ -114,9 +114,6 @@ struct parse_events_state {
 	int			   nr_groups;
 	struct parse_events_error *error;
 	struct perf_evlist	  *evlist;
-};
-
-struct parse_events_terms {
 	struct list_head	  *terms;
 };
 

tools/perf/util/parse-events.y

@@ -488,7 +488,7 @@ opt_event_config:
 
 start_terms: event_config
 {
-	struct parse_events_terms *data = _data;
+	struct parse_events_state *data = _data;
 	data->terms = $1;
 }