bug#45660: 28.0.50; Changed word/whitespace syntax

[Juri Linkov]

Some unidentified recent change during the last week broke the
definition of word syntax and whitespace syntax.  I noticed the
change of behavior in markchars-mode that now disregards the character
"NARROW NO-BREAK SPACE" as the word separator between thousands, i.e.:

In Emacs 27:
(and (string-match "\\<\\w+\\>" "4 096") (match-end 0))
1

In Emacs 28:
(and (string-match "\\<\\w+\\>" "4 096") (match-end 0))
5

Note there is the character "NARROW NO-BREAK SPACE" between "4" and "096".

Please close this bug report if this change was intentional
because if it provides more correct definitions
then other code could be adopted to such change.