build: i18n: support little-endian machines

Note that this may not affect anything until powerpc support lands in
v8.

Related: https://github.com/srl295/node/issues/7
Related: https://github.com/srl295/node/commit/ba8ab91bc4762ade646474276c4a4b8cdaf83115
PR-URL: https://github.com/joyent/node/pull/8712
Reviewed-by: Trevor Norris <trev.norris@gmail.com>