In some places there was still the old Unicode version 10.0.0 in the files.
* localedata/charmaps/UTF-8: Use correct Unicode version 11.0.0 in comment.
* localedata/locales/i18n_ctype: Use correct Unicode version in comments
and headers.
* localedata/unicode-gen/utf8_gen.py: Add option to specify Unicode version
* localedata/unicode-gen/Makefile: Use option to specify Unicode version
for utf8_gen.py
