i2psnark: Don't count unchoked but uninterested peers as uploaders

when calculating global uploader limit, to allow more upload slots,
especially when some torrents are stalled.
Convert some shared fields to atomics for concurrency.

router/java/src/net/i2p/router/RouterVersion.java

@@ -18,7 +18,7 @@ public class RouterVersion {
     /** deprecated */
     public final static String ID = "Monotone";
     public final static String VERSION = CoreVersion.VERSION;
-    public final static long BUILD = 3;
+    public final static long BUILD = 4;
 
     /** for example "-test" */
     public final static String EXTRA = "";