6743059: Error in spaceDecorator.cpp "optimized" build.

Summary: Changed the guard on the definition of the method value in HeapWord from ASSERT to not PRODUCT.
Reviewed-by: iveresov, apetrusenko

src/share/vm/utilities/globalDefinitions.hpp

@@ -99,7 +99,7 @@ class HeapWord {
   friend class VMStructs;
  private:
   char* i;
-#ifdef ASSERT
+#ifndef PRODUCT
  public:
   char* value() { return i; }
 #endif