mem_tracker: Return VK_SUCCESS in vkCreateCommandPool, vkResetCommandPool

Build on Windows was failing.
diff --git a/layers/mem_tracker.cpp b/layers/mem_tracker.cpp
index 4cbfb7d..46b697f 100644
--- a/layers/mem_tracker.cpp
+++ b/layers/mem_tracker.cpp
@@ -1877,6 +1877,7 @@
     // Add cmd pool to map
     my_data->commandPoolMap[*pCommandPool].createFlags = pCreateInfo->flags;
     loader_platform_thread_unlock_mutex(&globalLock);
+    return VK_SUCCESS;
 }
 
 VK_LAYER_EXPORT VKAPI_ATTR void VKAPI_CALL vkDestroyCommandPool(
@@ -1937,7 +1938,7 @@
             skipCall |= clear_cmd_buf_and_mem_references(my_data, (*it));
         }
     }
-
+    return VK_SUCCESS;
 }
 
 VK_LAYER_EXPORT VKAPI_ATTR VkResult VKAPI_CALL vkBeginCommandBuffer(