o Made lower bound of executor threads 0 for artifact resolver

Ideally I think we should just get rid of the whole executor and use new Thread() instead,
which would mean we'd need some way of constraining thread counts.

Freeing the threads mean they also release the classloader

maven-compat/src/main/java/org/apache/maven/artifact/resolver/DefaultArtifactResolver.java

@@ -111,7 +111,7 @@ public void execute( Runnable command )
         else
         {
             executor =
-                new ThreadPoolExecutor( threads, threads, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new DaemonThreadCreator());
+                new ThreadPoolExecutor( 0, threads, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new DaemonThreadCreator());
         }
     }