build: work around VS2015 issue in ICU <56

This change is a backport of
nodejs/node@4c06515a2f13c9b0890b374bb3ab3c0740c282e2.

Original commit message:

  The particular ufile.c is from
  http://bugs.icu-project.org/trac/changeset/37704


  and should be OK for ICU 54 and 55.

  Also, adds general mechanism for floating patches on top of ICU.

  Fixes: nodejs/node#2279
  PR-URL: nodejs/node#2283
Reviewed-By: João Reis <reis@janeasystems.com>

Fixes: #25792

PR-URL: https://github.com/joyent/node/pull/25804


Reviewed-By: João Reis <reis@janeasystems.com>