tracing: Change if (strlen(glob)) to if (glob[0])

No need to traverse to the end of string. If the first byte is not a NUL
char, it's guaranteed `if (strlen(glob))` is true.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Ingo Molnar <[email protected]>
Cc: GNU/Weeb Mailing List <[email protected]>
Signed-off-by: Ammar Faizi <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: ammarfaizi2

kernel/trace/trace_events_hist.c

@@ -6217,7 +6217,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 	if (WARN_ON(!glob))
 		return -EINVAL;
 
-	if (strlen(glob)) {
+	if (glob[0]) {
 		hist_err_clear();
 		last_cmd_set(file, param_and_filter);
 	}