Fix GPU Buffer Map/Unmap pair to prevent stall if map fails on DX11

#942

Source/Engine/Graphics/GPUBuffer.cpp

@@ -377,12 +377,9 @@ void GPUBuffer::SetData(const void* data, uint32 size)
         Log::ArgumentOutOfRangeException(TEXT("Buffer.SetData"));
         return;
     }
-
     void* mapped = Map(GPUResourceMapMode::Write);
     if (!mapped)
-    {
         return;
-    }
     Platform::MemoryCopy(mapped, data, size);
     Unmap();
 }

Source/Engine/Graphics/GPUBuffer.h

@@ -190,6 +190,7 @@ public:
     /// <summary>
     /// Gets a CPU pointer to the resource by mapping its contents. Denies the GPU access to that resource.
     /// </summary>
+    /// <remarks>Always call Unmap if the returned pointer is valid to release resources.</remarks>
     /// <param name="mode">The map operation mode.</param>
     /// <returns>The pointer of the mapped CPU buffer with resource data or null if failed.</returns>
     API_FUNCTION() virtual void* Map(GPUResourceMapMode mode) = 0;