build: intl: converge from joyent/node

* turn on small-icu by default for builds (Makefile+Windows)
* add license info from ICU
  http://source.icu-project.org/repos/icu/icu/trunk/license.html
  All text pasted. Long lines wrapped. (original is HTML.)

Port from joyent/node of:
* https://github.com/nodejs/node/issues/26
 * port of joyent/node 67f87a74
* https://github.com/joyent/node/pull/9038
 * Merge from joyent/node 70d04e7f
 * Merge from joyent/node 6168fe67
 * merge from joyent/node e6707325

PR-URL: https://github.com/nodejs/node/pull/2264


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rod Vagg <rod@vagg.org>
Fixes: https://github.com/nodejs/node/issues/238