Consistently use named parameters in regex code consistently.

Consistently use named parameters in regex code consistently.

Adjust a handful of remaining function prototypes that were overlooked
by recent commit bc2187ed.  This oversight wasn't caught by clang-tidy
because the functions in question are only built in custom REG_DEBUG
builds.

Author: Peter Geoghegan <pg@bowt.ie>
Reported-By: Tom Lane <tgl@sss.pgh.pa.us>