From: Andi Kleen <ak@muc.de>

It fixes the statfs64 emulation on x86-64.  The problem is that x86-64
needs an __attribute__((aligned)) on the compat_statfs64 structure.  The
conclusion last time this was discussed was that the structure should be
duplicated.

Essentially it is the old shared structure copied to every user and x86-64
uses __attribute__((packed)).