RFR: Ensure compensate when ForkJoinWorkerThread is pinned

[Miao Zheng]

Hello,
We have a test case about Loom, it can pass before;
The test case can be seen on this PR;
 
But it cannot pass after this patch:

commit de90a43c7a5f0b28bd0af9271de210475808ca0c
Author: Alan Bateman <alan.bateman at oracle.com>
Date:   Wed Sep 1 09:22:23 2021 +0100
 
    Replace lock/condition objects to simplify pinned park

 
Actually, this modify cause the test fail, because getCondition.await() will call tryCompensate() of ForkJoinPool eventually:

+    private void parkOnCarrierThread(long nanos) {

-                if (!parkPermit) {
-                    // wait to be signalled or interrupted
-                    getCondition().await();

+            if (!parkPermit) {
+                U.park(false, nanos);
             }
``` 
If ForkJoinWorkerThread are all pinned, how to make vt work correct?

Thanks，

Miao

-------------

Commit messages:
 - Ensure compensate when ForkJoinWorkerThread is pinned

Changes: https://git.openjdk.java.net/loom/pull/80/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=80&range=00
  Stats: 87 lines in 1 file changed: 87 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/loom/pull/80.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/80/head:pull/80

PR: https://git.openjdk.java.net/loom/pull/80