bug#29044: sort --debug results improvement

[積丹尼 Dan Jacobson]

< P.S., Yes indeed I had LC_COLLATE=C so maybe --debug should mention
< where in the environment it made it choices from too.

Ah, like you said

  $ LC_ALL=en_CA.UTF-8 sort --debug < /dev/null
  sort: using ‘en_CA.UTF-8’ sorting rules

  $ LC_ALL=C sort --debug < /dev/null
  sort: using simple byte comparison

So the last line should be
  sort: using 'C' sorting rules (simple byte comparison)

or maybe also say "effective LC_COLLATE value is ...."..