NH-3807 - Guard on use of DbProviderFactories for CoreClr.

Author: ngbrown

src/NHibernate/Driver/ReflectionBasedDriver.cs

@@ -41,12 +41,16 @@ protected ReflectionBasedDriver(string providerInvariantName, string driverAssem
 
 			if (connectionType == null || commandType == null)
 			{
+#if FEATURE_DBPROVIDERFACTORIES
 				if (string.IsNullOrEmpty(providerInvariantName))
 				{
 					throw new HibernateException(string.Format(ReflectionTypedProviderExceptionMessageTemplate, driverAssemblyName));
 				}
 				var factory = DbProviderFactories.GetFactory(providerInvariantName);
 				connectionCommandProvider = new DbProviderFactoryDriveConnectionCommandProvider(factory);
+#else
+				throw new HibernateException(string.Format(ReflectionTypedProviderExceptionMessageTemplate, driverAssemblyName));
+#endif
 			}
 			else
 			{
@@ -64,4 +68,4 @@ public override DbCommand CreateCommand()
 			return connectionCommandProvider.CreateCommand();
 		}
 	}
-}
+}