Revert "Re-add UTF8_ENABLED constant"

This reverts commit 25cb81297c4458f80bee353fd645861a8a90ee33.
diff --git a/system/core/Utf8.php b/system/core/Utf8.php
index 21bac60..1d5dfc2 100644
--- a/system/core/Utf8.php
+++ b/system/core/Utf8.php
@@ -57,8 +57,7 @@
 			&& @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
@@ -69,7 +68,6 @@
 		}
 		else
 		{
-			define('UTF8_ENABLED', FALSE);
 			log_message('debug', 'UTF-8 Support Disabled');
 		}
 	}