bug#57604: [ef]grep usage -> POSIXLY_CORRECT?

[Karl Berry]

    simpler solution to undeprecate the tools in documentation and have
    them be official GNU-enhancements as they de-facto has been for the
    past 20+ years

+20

    My pet issue was the inconsistency between documentation and reality, 

Agreed.

    I think the simplest way to fix that is to drop the tools

Not that anyone cares, but IMHO the simplest way is to delete the new
warning lines. End of problem.

    issue warnings: on some current systems (I think it was Alpine)
    is no egrep and fgrep any more

To my understanding, GNU should not cater to the lowest common
denominator, or be unfriendly to users. To quote from the coding
standards:

  Standard C and POSIX prohibit many kinds of extensions.  Feel
  free to make the extensions anyway ...
  ...
  But we do not follow either of these specifications [ANSI C and POSIX]
  rigidly, and there are specific points on which we decided not to
  follow them, so as to make the GNU system better for users.
  ...
  In particular, don't reject a new feature, or remove an old one,
                                             ^^^^^^^^^^^^^^^^^^^^
  merely because a standard says it is ``forbidden'' or ``deprecated''.

--karl