Call JNI_OnUnload when class loaders get collected

Added test case to 141-class-unload.

Bug: 22720414
Change-Id: I0575fae72521520a17587e8b0088bf8112705ad8
diff --git a/test/141-class-unload/src-ex/IntHolder.java b/test/141-class-unload/src-ex/IntHolder.java
index 0a1c1e6..b4651af 100644
--- a/test/141-class-unload/src-ex/IntHolder.java
+++ b/test/141-class-unload/src-ex/IntHolder.java
@@ -30,4 +30,8 @@
     public static void runGC() {
         Runtime.getRuntime().gc();
     }
+
+    public static void loadLibrary(String name) {
+        System.loadLibrary(name);
+    }
 }