A cross-emerge wrapper extracted from ambro-cross-overlay

This is the cross-emerge-ng tool from ambro-cross-overlay (https://code.google.com/p/ambro-cross-overlay/) without the surrounding crossdev.
Added ~amd64 keyword to xeon-phi binutils.
Gentoo packages with x86_64 assembly.
Modified assembly dependent ebuilds to work with k1om assembler.