fix build...

src/engine/dispatch.h

@@ -796,7 +796,7 @@ class DivDispatch {
      * @param index the memory index.
      * @return a pointer to DivMemoryComposition, or NULL.
      */
-    virtual const DivMemoryComposition* getMemCompo();
+    virtual const DivMemoryComposition* getMemCompo(int index);
 
     /**
      * Render samples into sample memory.

src/engine/platform/abstract.cpp

@@ -199,6 +199,10 @@ size_t DivDispatch::getSampleMemUsage(int index) {
   return 0;
 }
 
+const DivMemoryComposition* DivDispatch::getMemCompo(int index) {
+  return NULL;
+}
+
 bool DivDispatch::isSampleLoaded(int index, int sample) {
   printf("you are calling.\n");
   return false;