8067972: Bring changes made to WhiteBox.java in 8047290 to that file new location in the top repo

Reviewed-by: jcoomes

test/lib/sun/hotspot/WhiteBox.java

@@ -249,4 +249,6 @@ public class WhiteBox {
     return offset;
   }
 
+  // Safepoint Checking
+  public native void assertMatchingSafepointCalls(boolean mutexSafepointValue, boolean attemptedNoSafepointValue);
 }