"make install" fails because:

    1. port makefile invokes install.html target,
       which calls install.rhtml target

    2. install.rhtml, install.jhtml targets assume
       existence of $(DESTDIR)$(XFIGDOCDIR)
       (/usr/local/share/doc/xfig) and call, e.g.,
       "install xfig-howto.pdf $(DESTDIR)$(XFIGDOCDIR)"
       which causes $(DESTDIR)$(XFIGDOCDIR) to be a copy
       of the file.

    3. subsequent "mkdirhier /usr/local/share/doc/xfig/html"
       exits with error because /usr/local/share/doc/xfig is a file.

# cd /usr/ports/graphics/xfig
# make showconfig
===> The following configuration options are available for xfig-3.2.5_1:
     GHOSTSCRIPT=on "Ghostscript support"
     I18N=off "I18N support and Japanese docs"
===> Use 'make config' to modify these settings
# make install
..
Copying Fig Object Libraries
+ /usr/local/bin/mkdirhier /usr/local/lib/X11/xfig/Libraries
+ set +x
Copying pdf and html files to /usr/local/share/doc/xfig
+ /usr/local/bin/mkdirhier /usr/local/share/doc/xfig/html
mkdir: //usr/local/share/doc/xfig: File exists
mkdir: //usr/local/share/doc/xfig: No such file or directory
*** Error code 1

Stop in /usr/ports/graphics/xfig/work/xfig.3.2.5.
*** Error code 1

Fix: A few changes to Imakefile seems to correct the problem. Since there is already a files/patch-Imakefile, I herewith submit a patch to that patch.

Patch attached with submission follows:
How-To-Repeat: cd /usr/ports/graphics/xfig
make deinstall
make install