RevWalk: Make fields available to DepthWalk

DepthWalk needs to override toObjectWalkWithSameObjects() and thus
needs to be able to directly set the objects and freeFlags fields, so
make them package private.

Change-Id: I24561b82c54ba3d6522582ca25105b204d777074
Signed-off-by: Terry Parker <tparker@google.com>

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java

@@ -172,7 +172,7 @@ public class RevWalk implements Iterable<RevCommit>, AutoCloseable {
 
 	ObjectIdOwnerMap<RevObject> objects;
 
-	private int freeFlags = APP_FLAGS;
+	int freeFlags = APP_FLAGS;
 
 	private int delayFreeFlags;