Adding updating icon cache when install DaumCloud

Below is needed to update icon cache when installing/uninstalling
. src_prepare() { gnome2_icon_savelist; }
. pkg_postinst() { gnome2_icon_cache_update; }
. pkg_postrm() { gnome2_icon_cache_update; }

Signed-off-by: Kwanhong Lee <kwanhong.lee@windriver.com>