libtorrent: fixed by removing boost related workaround

Note:

Since boost 1.40.0 the multi-threaded version will be installed without "-mt"
suffix on Unix-a-like systems!

network/libtorrent/libtorrent.conf

@@ -1,20 +0,0 @@
-# --- SDE-COPYRIGHT-NOTE-BEGIN ---
-# This copyright note is auto-generated by ./scripts/Create-CopyPatch.
-#
-# Filename: package/.../libtorrent/libtorrent.conf
-# Copyright (C) 2007 - 2009 The OpenSDE Project
-#
-# More information can be found in the files COPYING and README.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; version 2 of the License. A copy of the
-# GNU General Public License can be found in the file COPYING.
-# --- SDE-COPYRIGHT-NOTE-END ---
-
-# libtorrent is unable to find boost threads on its own :-/
-for x in asio:system system filesystem thread regex python \
-	program_options; do
-
-	var_append confopt ' ' "--with-boost-${x%:*}=boost_${x#*:}-mt"
-done