Fix a few multiple enumerations

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -358,7 +358,7 @@ namespace Emby.Server.Implementations.Library
 
             var children = item.IsFolder
                 ? ((Folder)item).GetRecursiveChildren(false)
-                : Enumerable.Empty<BaseItem>();
+                : Array.Empty<BaseItem>();
 
             foreach (var metadataPath in GetMetadataPaths(item, children))
             {

MediaBrowser.Providers/Manager/ProviderManager.cs

@@ -807,13 +807,11 @@ namespace MediaBrowser.Providers.Manager
             where TLookupType : ItemLookupInfo
         {
             var results = await provider.GetSearchResults(searchInfo, cancellationToken).ConfigureAwait(false);
-
-            foreach (var item in results)
+            return results.Select(result =>
             {
-                item.SearchProviderName = provider.Name;
-            }
-
-            return results;
+                result.SearchProviderName = provider.Name;
+                return result;
+            });
         }
 
         private IEnumerable<IExternalId> GetExternalIds(IHasProviderIds item)