Harmonize lexer adjacent function parameter names.

Harmonize lexer adjacent function parameter names.

Make sure that function declarations use names that exactly match the
corresponding names from function definitions for several "lexer
adjacent" backend functions.

These functions were missed by recent commits because they were obscured
by clang-tidy warnings about functions whose signature is directly under
the control of the lexer (flex seems to always generate function
declarations with unnamed parameters).  We probably can't fix most of
the warnings it generates for translation units that get built from .l
and .y files, but we can at least do this much.

Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com