Just use normal getInstance to get KeyFactory

We have the provider in hand, so just use it to get the algorithm
using the available getInstance.

Fixes #197

Author: headius

src/main/java/org/jruby/ext/openssl/SecurityHelper.java

@@ -286,10 +286,7 @@ static KeyFactory getKeyFactory(final String algorithm, final Provider provider)
         throws NoSuchAlgorithmException {
         KeyFactorySpi spi = (KeyFactorySpi) getImplEngine("KeyFactory", algorithm);
         if ( spi == null ) throw new NoSuchAlgorithmException(algorithm + " not found");
-        return newInstance(KeyFactory.class,
-            new Class[] { KeyFactorySpi.class, Provider.class, String.class },
-            new Object[] { spi, provider, algorithm }
-        );
+        return KeyFactory.getInstance(algorithm, provider);
     }
 
     /**