Add some more missing @Override annotations

Change-Id: Ic13160920b986edde87c928c473240cc9c034f50
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/GcOrphanFilesTest.java

@@ -67,6 +67,7 @@ public class GcOrphanFilesTest extends GcTestCase {
 
 	private File packDir;
 
+	@Override
 	@Before
 	public void setUp() throws Exception {
 		super.setUp();

org.eclipse.jgit/src/org/eclipse/jgit/transport/RefLeaseSpec.java

@@ -89,6 +89,7 @@ public String getExpected() {
 		return expected;
 	}
 
+	@Override
 	public String toString() {
 		final StringBuilder r = new StringBuilder();
 		r.append(getRef());