regexes: Remove uses of ANYOF_LOCALE flag

regexes: Remove uses of ANYOF_LOCALE flag

This flag no longer adds any useful information and can be removed.  An
ANYOF node that depends on locale either matches a POSIX class like /d,
or matches case insensitively, or both.  There are flags for both these
cases, and to see if something matches locale, one merely needs to see
if either flag is set.

Not having to keep track of this extra flag simplifies things, and will
allow it to be removed.  There was a time when this flag was shared with
one of the remaining locale ones, and there was relict code that allowed
that sharing to be reinstated, and which this commit also removes.