Change upper limit handling of -Dr output

Change upper limit handling of -Dr output

Commit 2bfbbbaf9ef1783ba914ff9e9270e877fbbb6aba changed things so -Dr
output could be changed through an environment variable to truncate
the output differently than the default.

For most purposes, the default is good enough, but for someone trying to
debug the regcomp internals, sometimes one wants to see more than is
output by default.

That commit did not catch all the places.  This one changes the handling
so that any place that use the previous default maximum now uses the
environment variable (if set) instead.