perf tools: Add support for displaying event parser debug info

Adding PARSER_DEBUG Makefile variable to enable building event scanner/
parser with debug enabled. This results in verbose output right out of
the scanner/parser.

It's useful for debuging the event parser. Keeping this only for event
parser so far.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1337584373-2741-3-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -23,6 +23,9 @@ struct event_symbol {
 	const char	*alias;
 };
 
+#ifdef PARSER_DEBUG
+extern int parse_events_debug;
+#endif
 int parse_events_parse(struct list_head *list, struct list_head *list_tmp,
 		       int *idx);
 
@@ -768,6 +771,9 @@ int parse_events(struct perf_evlist *evlist, const char *str, int unset __used)
 
 	buffer = parse_events__scan_string(str);
 
+#ifdef PARSER_DEBUG
+	parse_events_debug = 1;
+#endif
 	ret = parse_events_parse(&list, &list_tmp, &idx);
 
 	parse_events__flush_buffer(buffer);