tools lib traceevent: Add const qualifier to string arguments

If pevent_register_event_handler() received a string literal as
@sys_name or @event_name parameter, it emitted a warning about const
qualifier removal.  Since they're not modified in the function we can
make it have const qualifier.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1370323231-14022-4-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/event-parse.c

@@ -5450,10 +5450,9 @@ int pevent_register_print_function(struct pevent *pevent,
  * If @id is >= 0, then it is used to find the event.
  * else @sys_name and @event_name are used.
  */
-int pevent_register_event_handler(struct pevent *pevent,
-				  int id, char *sys_name, char *event_name,
-				  pevent_event_handler_func func,
-				  void *context)
+int pevent_register_event_handler(struct pevent *pevent, int id,
+				  const char *sys_name, const char *event_name,
+				  pevent_event_handler_func func, void *context)
 {
 	struct event_format *event;
 	struct event_handler *handle;

tools/lib/traceevent/event-parse.h

@@ -561,7 +561,8 @@ int pevent_print_num_field(struct trace_seq *s, const char *fmt,
 			   struct event_format *event, const char *name,
 			   struct pevent_record *record, int err);
 
-int pevent_register_event_handler(struct pevent *pevent, int id, char *sys_name, char *event_name,
+int pevent_register_event_handler(struct pevent *pevent, int id,
+				  const char *sys_name, const char *event_name,
 				  pevent_event_handler_func func, void *context);
 int pevent_register_print_function(struct pevent *pevent,
 				   pevent_func_handler func,