Replace AtomicBoolean with volatile boolean field. (#796)

Atomic's are good when you need CAS. If you need only read/write from different threads, volatile is enough.

terminal/src/main/java/org/jline/terminal/impl/PosixPtyTerminal.java

@@ -15,7 +15,6 @@
 import java.io.PrintWriter;
 import java.nio.charset.Charset;
 import java.util.Objects;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.jline.terminal.spi.Pty;
 import org.jline.utils.ClosedException;
@@ -146,23 +145,23 @@ public boolean paused() {
     private static class InputStreamWrapper extends NonBlockingInputStream {
 
         private final NonBlockingInputStream in;
-        private final AtomicBoolean closed = new AtomicBoolean();
+        private volatile boolean closed;
 
         protected InputStreamWrapper(NonBlockingInputStream in) {
             this.in = in;
         }
 
         @Override
         public int read(long timeout, boolean isPeek) throws IOException {
-            if (closed.get()) {
+            if (closed) {
                 throw new ClosedException();
             }
             return in.read(timeout, isPeek);
         }
 
         @Override
         public void close() throws IOException {
-            closed.set(true);
+            closed = true;
         }
     }