Fix build again

Author: ejsmith

samples/Foundatio.HostingSample/Program.cs

@@ -15,7 +15,9 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
+#if REDIS
 using StackExchange.Redis;
+#endif
 
 bool all = args.Contains("all", StringComparer.OrdinalIgnoreCase);
 bool sample1 = all || args.Contains("sample1", StringComparer.OrdinalIgnoreCase);