[tlbuild] ICU library moves from IBM to Unicode Consortium

[Nelson H. F. Beebe]

While it does not affect TeX Live 2016, it could well be important for
TeX Live 2017:

	ICU joins the Unicode Consortium
	http://blog.unicode.org/2016/05/icu-joins-unicode-consortium.html

That announces the transfer of the libicu (International Components
for Unicode) library code from IBM to the Unicode Consortium.

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- Nelson H. F. Beebe                    Tel: +1 801 581 5254                  -
- University of Utah                    FAX: +1 801 581 4148                  -
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