Project:AMD64/Multilib layout

At this moment, Gentoo supports two different multilib layouts for AMD64. The main difference between those layouts is the presence of symlink. They are therefore informally called the SYMLINK_LIB=yes and SYMLINK_LIB=no layouts.

SYMLINK_LIB=yes layout (old)
The main feature of this layout is the presence of ``lib`` compatibility symlink. In this layout:
 * 64-bit libraries are installed into directory,
 * 32-bit libraries are installed into directory,
 * is a symlink to, so packages installed into are actually installed to the  directory.

SYMLINK_LIB=no layout (17.1 profiles)
In this layout, the compatibility symlink is removed, and canonical directories are used. That is:
 * 64-bit libraries are installed into directory,
 * 32-bit libraries are installed into directory,
 * is a real directory, so packages using that directory are not moved to.