Fix cross compilation, based on OpenWRT patch.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

diff -Nura libtorrent-0.13.2/configure.ac libtorrent-0.13.2-cross/configure.ac
--- libtorrent-0.13.2/configure.ac	2012-04-20 03:55:10.000000000 -0300
+++ libtorrent-0.13.2-cross/configure.ac	2012-05-09 10:57:49.671175421 -0300
@@ -17,7 +17,6 @@
 
 AM_INIT_AUTOMAKE
 AM_CONFIG_HEADER(config.h)
-AM_PATH_CPPUNIT(1.9.6)
 AC_DISABLE_STATIC
 
 AM_DISABLE_STATIC
diff -Nura libtorrent-0.13.2/scripts/checks.m4 libtorrent-0.13.2-cross/scripts/checks.m4
--- libtorrent-0.13.2/scripts/checks.m4	2012-04-12 06:44:23.000000000 -0300
+++ libtorrent-0.13.2-cross/scripts/checks.m4	2012-05-09 10:42:32.642728917 -0300
@@ -96,7 +96,7 @@
 AC_DEFUN([TORRENT_CHECK_KQUEUE_SOCKET_ONLY], [
   AC_MSG_CHECKING(whether kqueue supports pipes and ptys)
 
-  AC_RUN_IFELSE([AC_LANG_SOURCE([
+  AC_LINK_IFELSE([AC_LANG_SOURCE([
       #include <fcntl.h>
       #include <stdlib.h>
       #include <unistd.h>