tools lib traceevent: Add __maybe_unused to unused parameters

Fixing the build on 32-bit Fedora 14:

  tools/lib/traceevent/event-parse.c: In function ‘print_event_fields’:
  tools/lib/traceevent/event-parse.c:3934:69: error: unused parameter ‘size’
  tools/lib/traceevent/event-parse.c: In function ‘pevent_strerror’:
  tools/lib/traceevent/event-parse.c:5074:36: error: unused parameter ‘pevent’

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-soe4gqcz8fd4ecik6exvyqox@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/event-parse.c

@@ -3931,7 +3931,8 @@ static int is_printable_array(char *p, unsigned int len)
 	return 1;
 }
 
-static void print_event_fields(struct trace_seq *s, void *data, int size,
+static void print_event_fields(struct trace_seq *s, void *data,
+			       int size __maybe_unused,
 			       struct event_format *event)
 {
 	struct format_field *field;
@@ -5070,8 +5071,8 @@ static const char * const pevent_error_str[] = {
 };
 #undef _PE
 
-int pevent_strerror(struct pevent *pevent, enum pevent_errno errnum,
-		    char *buf, size_t buflen)
+int pevent_strerror(struct pevent *pevent __maybe_unused,
+		    enum pevent_errno errnum, char *buf, size_t buflen)
 {
 	int idx;
 	const char *msg;