testutil: return 1 on success

Require that test methods return 1 on success (not 0). This is more
customary for OpenSSL.

Reviewed-by: Rich Salz <rsalz@openssl.org>
diff --git a/test/d2i_test.c b/test/d2i_test.c
index cf01012..6ffdf55 100644
--- a/test/d2i_test.c
+++ b/test/d2i_test.c
@@ -40,13 +40,13 @@
 {
     BIO *bio = NULL;
     ASN1_VALUE *value = NULL;
-    int ret = 1;
+    int ret = 0;
     unsigned char buf[2048];
     const unsigned char *buf_ptr = buf;
     int len;
 
     if ((bio = BIO_new_file(test_file, "r")) == NULL)
-        return 1;
+        return 0;
 
     /*
      * We don't use ASN1_item_d2i_bio because it, apparently,
@@ -60,7 +60,7 @@
     if (value != NULL)
         goto err;
 
-    ret = 0;
+    ret = 1;
 
  err:
     BIO_free(bio);