Fix $t_path variable not found error from last commit

The forward port of 782a7e0 was
incorrect as it removed a line of code that was essential. My bad!

config_defaults_inc.php

@@ -126,6 +126,7 @@
 		$t_host = 'localhost';
 	}
 
+	$t_path = str_replace( basename( $_SERVER['PHP_SELF'] ), '', $_SERVER['PHP_SELF'] );
 	$t_path = basename( $t_path ) == "admin" ? dirname( $t_path ) . DIRECTORY_SEPARATOR : $t_path;
 	$t_url	= $t_protocol . '://' . $t_host . $t_path;