[Perl/perl5] 332f44: regcomp.c: Add invlist_lowest() and use it

[Karl Williamson]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 332f44b7fda4d21503e806a594af30ad4109c290
      
https://github.com/Perl/perl5/commit/332f44b7fda4d21503e806a594af30ad4109c290
  Author: Karl Williamson <k...@cpan.org>
  Date:   2019-11-20 (Wed, 20 Nov 2019)

  Changed paths:
    M embed.fnc
    M embed.h
    M proto.h
    M regcomp.c

  Log Message:
  -----------
  regcomp.c: Add invlist_lowest() and use it

This makes it less complicated to find the lowest code point in an
inversion list.  This makes the place where it's used clearer as to what
is going on.  And it may eventually be used in more than one place.