Use CHARSET in FileOutputStream instead of hard-coded "UTF-8"

Change-Id: I63ad25e1ebd94081c8848f4d21044cf9041f971d
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/NetRCTest.java

@@ -42,6 +42,7 @@
 
 package org.eclipse.jgit.transport;
 
+import static org.eclipse.jgit.lib.Constants.CHARSET;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 
@@ -75,7 +76,7 @@ public class NetRCTest extends RepositoryTestCase {
 
 	private void config(final String data) throws IOException {
 		try (OutputStreamWriter fw = new OutputStreamWriter(
-				new FileOutputStream(configFile), "UTF-8")) {
+				new FileOutputStream(configFile), CHARSET)) {
 			fw.write(data);
 		}
 	}

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/OpenSshConfigTest.java

@@ -43,6 +43,7 @@
 
 package org.eclipse.jgit.transport;
 
+import static org.eclipse.jgit.lib.Constants.CHARSET;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -93,7 +94,7 @@ public class OpenSshConfigTest extends RepositoryTestCase {
 		long lastMtime = configFile.lastModified();
 		do {
 			try (final OutputStreamWriter fw = new OutputStreamWriter(
-					new FileOutputStream(configFile), "UTF-8")) {
+					new FileOutputStream(configFile), CHARSET)) {
 				fw.write(data);
 			}
 		} while (lastMtime == configFile.lastModified());