The Makefile already uses the proper autoreconf fixup but leaves a manual
autoconf invocation in place.

The bad autoconf call leads to the following build error in the SDK:

	( cd .../rtorrent-0.9.4-git; ./autogen.sh );
	aclocal...
	autoheader...
	libtoolize... libtoolize nor glibtoolize not found
	make[2]: *** [.../rtorrent-0.9.4-git/.configured_] Error 1

Remove the entire Build/Configure override to let rtorrent build correctly.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>