[MGPG-99] Make sure newline is added to input stream (#76)

When passphrase is being supplied with `--passphrase-fd 0`.

---

https://issues.apache.org/jira/browse/MGPG-99

Author: cstamas

src/main/java/org/apache/maven/plugins/gpg/GpgSigner.java

@@ -108,7 +108,11 @@ protected void generateSignatureForFile(File file, File signature) throws MojoEx
             cmd.createArg().setValue("0");
 
             // Prepare the input stream which will be used to pass the passphrase to the executable
-            in = new ByteArrayInputStream(passphrase.getBytes());
+            if (!passphrase.endsWith(System.lineSeparator())) {
+                in = new ByteArrayInputStream((passphrase + System.lineSeparator()).getBytes());
+            } else {
+                in = new ByteArrayInputStream(passphrase.getBytes());
+            }
         }
 
         if (null != keyname) {