Enable serving upload requests using bitmaps.

If the pack index has bitmaps, allow the PackWriter to use the bitmaps
for upload requests.

Change-Id: Iefa995fe927a11e4fd78afb34530995614221fc0

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

@@ -277,6 +277,7 @@ public abstract class BasePackPushConnection extends BasePackConnection implemen
 			}
 
 			writer.setUseCachedPacks(true);
+			writer.setUseBitmaps(true);
 			writer.setThin(thinPack);
 			writer.setReuseValidatingObjects(false);
 			writer.setDeltaBaseAsOffset(capableOfsDelta);

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

@@ -1137,6 +1137,7 @@ public class UploadPack {
 		final PackWriter pw = new PackWriter(cfg, walk.getObjectReader());
 		try {
 			pw.setUseCachedPacks(true);
+			pw.setUseBitmaps(true);
 			pw.setReuseDeltaCommits(true);
 			pw.setDeltaBaseAsOffset(options.contains(OPTION_OFS_DELTA));
 			pw.setThin(options.contains(OPTION_THIN_PACK));