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:
* #26
 * port of joyent/node 67f87a7
* nodejs/node-v0.x-archive#9038
 * Merge from joyent/node 70d04e7
 * Merge from joyent/node 6168fe6
 * merge from joyent/node e670732

PR-URL: #2264
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Rod Vagg <[email protected]>
Fixes: #238