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/testutil.h b/test/testutil.h
index ba54ac1..2ae3d7d 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -68,7 +68,7 @@
  *
  * EXECUTE_TEST will pass fixture to execute_func() by value, call
  * tear_down(), and return the result of execute_func(). execute_func() should
- * take a TEST_FIXTURE_TYPE by value and return zero on success or one on
+ * take a TEST_FIXTURE_TYPE by value and return 1 on success and 0 on
  * failure.
  *
  * Unit tests can define their own SETUP_TEST_FIXTURE and EXECUTE_TEST
@@ -94,7 +94,7 @@
     int result = 0
 
 # define EXECUTE_TEST(execute_func, tear_down)\
-        if (execute_func(fixture) != 0) result = 1;\
+        result = execute_func(fixture);\
         tear_down(fixture);\
         return result