[Truffle] MRI Kernel#gets always includes the trailing '\n'.

And it's always '\n' regardles of platform.

Author: nirvdrum

truffle/src/main/java/org/jruby/truffle/nodes/core/KernelNodes.java

@@ -876,7 +876,7 @@ public String block() throws InterruptedException {
         @TruffleBoundary
         private static String gets(BufferedReader reader) throws InterruptedException {
             try {
-                return reader.readLine();
+                return reader.readLine() + "\n";
             } catch (IOException e) {
                 throw new RuntimeException(e);
             }