[16/n] Internal 4GB allocator.

- simplify os agnostic memory manager
- remove pointer map
- move cpuPtr allocate logic to graphics allocation
- do not release tag allocation while injecting memory manager
- remove not needed ref count from Memory Allocation

Change-Id: I6ad81ee919c9cde939bc754a9dfc2db7568397d2

runtime/memory_manager/graphics_allocation.h

@@ -127,6 +127,7 @@ class GraphicsAllocation : public IDNode<GraphicsAllocation> {
     void incReuseCount() { reuseCount++; }
     void decReuseCount() { reuseCount--; }
     uint32_t peekReuseCount() const { return reuseCount; }
+    bool cpuPtrAllocated = false; // flag indicating if cpuPtr is driver-allocated
 
   private:
     int allocationType;