install-html and install-pdf improvements

[Tom Tromey]

>>>>> "Eli" == Eli Zaretskii <eliz@gnu.org> writes:

Joseph> The default definitions of htmldir and pdfdir use ${docdir}

Eli> Sorry, I'm not following: what default definitions?

See the top level configure.ac.  E.g.

AC_ARG_WITH(htmldir,
[  --with-htmldir          install html in this directory.],
[htmldir="\${prefix}/${withval}"],
[htmldir="\${docdir}"])

Tom