selftests/bpf: fix file resource leak in load_kallsyms

FILE pointer variable f is opened but never closed.
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/trace_helpers.c

@@ -41,6 +41,7 @@ int load_kallsyms(void)
 		syms[i].name = strdup(func);
 		i++;
 	}
+	fclose(f);
 	sym_cnt = i;
 	qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
 	return 0;