src/java.base/share/classes/java/util/concurrent/locks/StampedLock.java

8234131: Miscellaneous changes imported from jsr166 CVS 2020-12
Reviewed-by: martin

*** 210,221 ****
   *       if (StampedLock.isWriteLockStamp(stamp))
   *         sl.unlockWrite(stamp);
   *     }
   *   }
   *
!  *   // Upgrade read lock to write lock
!  *   void moveIfAtOrigin(double newX, double newY) {
   *     long stamp = sl.readLock();
   *     try {
   *       while (x == 0.0 && y == 0.0) {
   *         long ws = sl.tryConvertToWriteLock(stamp);
   *         if (ws != 0L) {
--- 210,221 ----
   *       if (StampedLock.isWriteLockStamp(stamp))
   *         sl.unlockWrite(stamp);
   *     }
   *   }
   *
!  *   // upgrade read lock to write lock
!  *   void moveIfAtOrigin2(double newX, double newY) {
   *     long stamp = sl.readLock();
   *     try {
   *       while (x == 0.0 && y == 0.0) {
   *         long ws = sl.tryConvertToWriteLock(stamp);
   *         if (ws != 0L) {