Remove unused defines from CI_Utf8
diff --git a/system/core/Utf8.php b/system/core/Utf8.php
index ba35674..1d5dfc2 100644
--- a/system/core/Utf8.php
+++ b/system/core/Utf8.php
@@ -57,26 +57,17 @@
 			&& @ini_get('mbstring.func_overload') != 1	// Multibyte string function overloading cannot be enabled
 			&& $CFG->item('charset') === 'UTF-8'		// Application charset must be UTF-8
 			)
-		{
-			define('UTF8_ENABLED', TRUE);
+		{			
 			log_message('debug', 'UTF-8 Support Enabled');
 
 			// set internal encoding for multibyte string functions if necessary
-			// and set a flag so we don't have to repeatedly use extension_loaded()
-			// or function_exists()
 			if (extension_loaded('mbstring'))
 			{
-				define('MB_ENABLED', TRUE);
 				mb_internal_encoding('UTF-8');
 			}
-			else
-			{
-				define('MB_ENABLED', FALSE);
-			}
 		}
 		else
 		{
-			define('UTF8_ENABLED', FALSE);
 			log_message('debug', 'UTF-8 Support Disabled');
 		}
 	}