maint: Use consistent coding style for build helper shell scripts * mk-octave-config-h.sh: Keep if-then on a single line. * move-if-change: Insert a space in interpreter directive for consistency. * build-env-features.sh, config-images.sh, config-module.sh, config-ops.sh, find-defun-files.sh, find-files-with-tests.sh, mk-errno-list, libinterp/mk-pkg-add, scripts/mk-pkg-add, mkbuiltins, mkdefs, mkdocs, mkf77def.in, mkops: Initialize environment variable defaults consistently. Use shift only when the argument list is not empty. Remove unnecessary quotes and semicolons on variable assignments. Insert/remove blank lines for consistency.

#! /bin/sh

set -e

AWK=${AWK:-awk}

if [ $# -eq 1 ]; then
  top_srcdir="$1"
else
  top_srcdir="../.."
fi

move_if_change="$top_srcdir/build-aux/move-if-change"

interp_dir=$top_srcdir/doc/interpreter

$AWK -v dir=doc/interpreter -f $interp_dir/images.awk < $interp_dir/images > $interp_dir/images.mk-t

$move_if_change $interp_dir/images.mk-t $interp_dir/images.mk