Broken links to Unicode pages in current UCD files

[Karl Williamson]

Someone discovered and reported various broken links.

An example is

# BidiMirroring-13.0.0.txt
# Date: 2019-09-09, 19:34:00 GMT [KW, LI, RP]
# © 2019 Unicode®, Inc.
# For terms of use, see http://www.unicode.org/terms_of_use.html

On line number 43, there is a link to

http://www.unicode.org/unicode/reports/tr9/

Following that link leads to a 404.

A link that works is http://www.unicode.org/reports/tr9/

Presumably the link in the file used to work.  One of the first rules of 
web design is to never ever break a published link.  It's fine to 
reorganize your site; just be sure that the original links are available 
as synonyms to the modern version.

In this case, the current UCD contains broken links.