Use new setup_tests in code of rsa_test

Although this piece of code will not be compiled at current stage, but
there seems a plan to re-open the 'no-rsa' option in the future so this
should be fixed.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4161)

test/rsa_test.c

@@ -22,9 +22,10 @@
 #include "testutil.h"
 
 #ifdef OPENSSL_NO_RSA
-void setup_tests(void)
+int setup_tests(void)
 {
     /* No tests */
+    return 1;
 }
 #else
 # include <openssl/rsa.h>