Add comment about X509_print

Signed-off-by: NKurt Roeckx <kurt@roeckx.be>
Reviewed-by: NEmilia Kasper <emilia@openssl.org>

GH: #1255

fuzz/x509.c

@@ -19,6 +19,7 @@ int FuzzerTestOneInput(const uint8_t *buf, size_t len) {
     X509 *x509 = d2i_X509(NULL, &p, len);
     if (x509 != NULL) {
         BIO *bio = BIO_new(BIO_s_null());
+        /* This will load and print the public key as well as extensions */
         X509_print(bio, x509);
         BIO_free(bio);