Fix typo in FFIVariablesCodeGen

com.oracle.truffle.r.ffi.codegen/src/com/oracle/truffle/r/ffi/codegen/FFIVariablesCodeGen.java

@@ -36,7 +36,7 @@ public class FFIVariablesCodeGen {
      */
     public static void main(String[] args) {
         System.out.println("// Update com.oracle.truffle.r.native/fficall/src/common/rffi_variablesindex.h with the following: \n");
-        System.out.println("// Generated by RFFIVariables.java:\n");
+        System.out.printf("// Generated by %s\n\n", FFIVariablesCodeGen.class.getSimpleName());
         for (RFFIVariables var : RFFIVariables.values()) {
             System.out.printf("#define %s_x %d\n", var.name(), var.ordinal());
         }
@@ -44,7 +44,7 @@ public class FFIVariablesCodeGen {
 
         System.out.println("\n\n// Update com.oracle.truffle.r.native/fficall/src/truffle_nfi/variables.c with the following: \n");
 
-        System.out.println("// Generated by RFFIVariables.java:\n");
+        System.out.printf("// Generated by %s\n\n", FFIVariablesCodeGen.class.getSimpleName());
 
         for (RFFIVariables val : RFFIVariables.values()) {
             if (val == RFFIVariables.R_Interactive) {