Merge branch 'jc/remove-export-from-config-mak-in'

Stop exporting mandir that used to be exported only when config.mak.autogen was used. It would have broken installation of manpages (but not other documentation formats). * jc/remove-export-from-config-mak-in: Fix `make install` when configured with autoconf Makefile: do not export mandir/htmldir/infodir config.mak.in: remove unused definitions