minor style fix

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/ffi/CallRFFI.java

@@ -62,7 +62,7 @@ public interface CallRFFI {
     }
 
     interface HandleUpCallExceptionNode extends NodeInterface {
-        abstract void execute(Throwable ex);
+        void execute(Throwable ex);
 
         static HandleUpCallExceptionNode create() {
             return RFFIFactory.getCallRFFI().createHandleUpCallExceptionNode();