Mine

$(PKG_BUILD_DIR)/.configured: $(PKG_BUILD_DIR)/.prepared
        (cd $(PKG_BUILD_DIR); \
                $(TARGET_CONFIGURE_OPTS) \
                CFLAGS="$(TARGET_CFLAGS)" \
                CPPFLAGS="-I$(STAGING_DIR)/usr/include -I$(STAGING_DIR)/include" \
                LDFLAGS="-L$(STAGING_DIR)/usr/lib -L$(STAGING_DIR)/lib" \
                ./configure \
                        --target=$(GNU_TARGET_NAME) \
                        --host=$(GNU_TARGET_NAME) \
                        --build=$(GNU_HOST_NAME) \
                        --prefix=/usr \
                        --exec-prefix=/usr \
        );
        touch $@

$(PKG_BUILD_DIR)/.built:
        rm -rf $(PKG_INSTALL_DIR)
        mkdir -p $(PKG_INSTALL_DIR)/usr/bin
        $(MAKE) -C $(PKG_BUILD_DIR)/src \
                $(TARGET_CONFIGURE_OPTS) \
                prefix="$(PKG_INSTALL_DIR)/usr"
#       cp -fpR $(PKG_BUILD_DIR)/src/.libs/libtorrent.la $(PKG_INSTALL_DIR)/usr/lib
        touch $@

$(IPKG_LIBTORRENT):
        install -d -m0755 $(IDIR_LIBTORRENT)/src/.libs
        cp -fpR $(PKG_INSTALL_DIR)/usr/lib/ $(IDIR_LIBTORRENT)/usr/lib
#       cp -fpR $(PKG_INSTALL_DIR)/usr/bin/hello $(IDIR_LIBTORRENT)/usr/bin
        $(RSTRIP) $(IDIR_LIBTORRENT)
        $(IPKG_BUILD) $(IDIR_LIBTORRENT) $(PACKAGE_DIR)

mostlyclean:
        make -C $(PKG_BUILD_DIR) clean
        rm $(PKG_BUILD_DIR)/.built