jvmballoon: fix _soft_max_balloons check

Number of to be released balloons is calculated as a difference between
current number of balloons and sof max. If they are equal no balloons
are released and the loop repeats.

Signed-off-by: Gleb Natapov <gleb@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

java/jvm_balloon.cc

@@ -295,7 +295,7 @@ void jvm_balloon_shrinker::_thread_loop()
         WITH_LOCK(balloons_lock) {
             _blocked.wait_until(balloons_lock, [&] { return (_pending.load() + _pending_release.load()) > 0; });
 
-            if (balloons.size() >= _soft_max_balloons) {
+            if (balloons.size() > _soft_max_balloons) {
                 memory::wake_reclaimer();
             }