* build host tar by default and use it to unpack some (not yet all) tarballs


git-svn-id: file:///var/svn/freetz/trunk@12588 149334a1-2f27-0410-a3b9-fc62619ac1e6
 * remove invalid comment, should've been removed in r9816


git-svn-id: file:///var/svn/freetz/trunk@12589 149334a1-2f27-0410-a3b9-fc62619ac1e6
 * cleanup toolchain/make/download-toolchain.mk


git-svn-id: file:///var/svn/freetz/trunk@12590 149334a1-2f27-0410-a3b9-fc62619ac1e6
 * introduce & use a variable for UNPACK_TARBALL prerequisites


git-svn-id: file:///var/svn/freetz/trunk@12591 149334a1-2f27-0410-a3b9-fc62619ac1e6