Source changes that follow Doug's mail on lambda-libs-spec-observers

http://mail.openjdk.java.net/pipermail/lambda-libs-spec-observers/2013-August/002361.html

These changes are already in the jsr166 CVS, and there is a test in OpenJDK that verifies the change.

diff --git a/src/share/classes/java/util/concurrent/ForkJoinPool.java b/src/share/classes/java/util/concurrent/ForkJoinPool.java
--- a/src/share/classes/java/util/concurrent/ForkJoinPool.java
+++ b/src/share/classes/java/util/concurrent/ForkJoinPool.java
@@ -144,7 +144,8 @@ import java.util.concurrent.TimeUnit;
  * Upon any error in establishing these settings, default parameters
  * are used. It is possible to disable or limit the use of threads in
  * the common pool by setting the parallelism property to zero, and/or
- * using a factory that may return {@code null}.
+ * using a factory that may return {@code null}. However doing so may
+ * cause unjoined tasks to never be executed.
  *
  * <p><b>Implementation notes</b>: This implementation restricts the
  * maximum number of running threads to 32767. Attempts to create
@@ -3303,8 +3304,8 @@ public class ForkJoinPool extends Abstra
         }

         if (parallelism < 0 && // default 1 less than #cores
- (parallelism = Runtime.getRuntime().availableProcessors() - 1) < 0)
- parallelism = 0;
+ (parallelism = Runtime.getRuntime().availableProcessors() - 1) <= 0)
+ parallelism = 1;
         if (parallelism > MAX_CAP)
             parallelism = MAX_CAP;
         return new ForkJoinPool(parallelism, factory, handler, LIFO_QUEUE,