perf trace-event-info: Avoid passing NULL value to closedir

If opendir failed then closedir was passed NULL which is
erroneous. Caught by clang-tidy.

Signed-off-by: Ian Rogers <[e-mail]>
Acked-by: Namhyung Kim <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Nick Desaulniers <[e-mail]>
Cc: Yang Jihong <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: [e-mail]
Cc: Ming Wang <[e-mail]>
Cc: Tom Rix <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/trace-event-info.c

···
 	}
 	err = 0;
 out:
-	closedir(dir);
+	if (dir)
+		closedir(dir);
 	put_tracing_file(path);
 
 	return err;