Bug: configure parameters ignored

I'm the FreeBSD port maintainer for GNU indent. It seems that at least
the following parameters of the configure script are ignored:

	--docdir
	--dvidir
	--psdir
	--pdfdir
	--htmldir

I know next to nothing about autotools (and have currently no
inclination to read up on it) but it seems to me that the lines

	docdir = $(prefix)/doc/@PACKAGE@
	dvidir = $(docdir)
	psdir = $(docdir)
	pdfdir = $(docdir)
	htmldir = $(docdir)

in doc/Makefile.in should read

	docdir = @docdir@
	dvidir = @dvidir@
	psdir =  @psdir@
	pdfdir = @pdfdir@
	htmldir = @htmldir@

How one gets automake to do this, I don't really know. It probably has
to do with the corresponding entries in doc/Makefile.am. But you guys
will know better how to fix this.