Include code to run binaries for the x32 native 32-bit ABI
for 64-bit processors. An x32 process gets access to the
full 64-bit register file and wide data path while leaving
pointers at 32 bits for smaller memory footprint.
You will need a recent binutils (2.22 or later) with
elf32_x86_64 support enabled to compile a kernel with this
option set.