perf tools: Increase MAX_EVENT_LENGTH

The name length of some trace events is longer than 30, like
sys_enter_sched_get_priority_max and
ext4_mb_discard_preallocations.

Passing those events to perf-record will fail, try:

  # ./perf record -f -e syscalls:sys_enter_sched_get_priority_max -F 1 -a
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4AB1F4AB.7050205@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/util/parse-events.c

@@ -145,7 +145,7 @@ static int tp_event_has_id(struct dirent *sys_dir, struct dirent *evt_dir)
 	   (strcmp(evt_dirent.d_name, "..")) &&				       \
 	   (!tp_event_has_id(&sys_dirent, &evt_dirent)))
 
-#define MAX_EVENT_LENGTH 30
+#define MAX_EVENT_LENGTH 512
 
 int valid_debugfs_mount(const char *debugfs)
 {