Make the port ready to have slave ports for cross building targets


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@366582 35697150-7ecd-e111-bb59-0022644237b5
New arm-gnueabi-binutils cross binutils support FreeBSD arm


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@366583 35697150-7ecd-e111-bb59-0022644237b5