Merge branch '3.0'

phpseclib/Crypt/RSA.php

@@ -327,6 +327,7 @@ abstract class RSA extends AsymmetricKey
                 openssl_pkey_export($rsa, $privatekeystr, null, $config);
 
                 // clear the buffer of error strings stemming from a minimalistic openssl.cnf
+                // https://github.com/php/php-src/issues/11054 talks about other errors this'll pick up
                 while (openssl_error_string() !== false) {
                 }