glr.cc: no longer require location support

* data/glr.cc: Use b4_locations_if where appropriate.
* data/lalr1.cc: M4 quotation changes to highlight code duplication
with glr.cc.
* tests/calc.at: Check glr.cc with and without %location.
While at it, fuse multiple %parse-params into one.
* tests/actions.at: Simplify.
* NEWS: Doc this.
Some other wording changes.