build: Enable declaration hiding warning on Windows

Fixes #1388
Turn on the Windows compiler option (4456) to report
hidden declarations.
Fix all places where this was occurring.

Change-Id: I3346d87da8b70d6299c206fcac68520a091ed1a6
diff --git a/layers/object_tracker.cpp b/layers/object_tracker.cpp
index 6b854be..f4acbe3 100644
--- a/layers/object_tracker.cpp
+++ b/layers/object_tracker.cpp
@@ -4338,7 +4338,7 @@
     if (dev_data->dispatch_table.RegisterDeviceEventEXT) {
         result = dev_data->dispatch_table.RegisterDeviceEventEXT(device, pDeviceEventInfo, pAllocator, pFence);
         if (result == VK_SUCCESS && pFence != NULL) {
-            std::lock_guard<std::mutex> lock(global_lock);
+            std::lock_guard<std::mutex> create_lock(global_lock);
             CreateObject(device, *pFence, VK_DEBUG_REPORT_OBJECT_TYPE_FENCE_EXT, pAllocator);
         }
     }
@@ -4360,7 +4360,7 @@
     if (dev_data->dispatch_table.RegisterDisplayEventEXT) {
         result = dev_data->dispatch_table.RegisterDisplayEventEXT(device, display, pDisplayEventInfo, pAllocator, pFence);
         if (result == VK_SUCCESS && pFence != NULL) {
-            std::lock_guard<std::mutex> lock(global_lock);
+            std::lock_guard<std::mutex> create_lock(global_lock);
             CreateObject(device, *pFence, VK_DEBUG_REPORT_OBJECT_TYPE_FENCE_EXT, pAllocator);
         }
     }