0.7007 build problems on OpenBSD 2.9

[Joshua Stein <jcs rt fm>]

I'm working on adding Gtk-Perl to the OpenBSD ports collection, but I'm
encountering a few build problems:

   [...]
   cp ImlibImage.bs blib/arch/auto/Gtk/Gdk/ImlibImage/ImlibImage.bs
   chmod 644 blib/arch/auto/Gtk/Gdk/ImlibImage/ImlibImage.bs
   mkdir blib/lib/auto/Gtk
   mkdir blib/lib/auto/Gtk/Gdk
   mkdir blib/lib/auto/Gtk/Gdk/ImlibImage
   usage: chmod [-R [-H | -L | -P]] mode file ...
   *** Error code 1 (ignored)
   Manifying /Gtk::Gdk::ImlibImage::reference.3pm
   sh: cannot create /Gtk::Gdk::ImlibImage::reference.3pm: Permission denied
   Couldn't install /Gtk::Gdk::ImlibImage::reference.3pm
   [...]
   cp Pixbuf.bs blib/arch/auto/Gtk/Gdk/Pixbuf/Pixbuf.bs
   chmod 644 blib/arch/auto/Gtk/Gdk/Pixbuf/Pixbuf.bs
   mkdir blib/lib/auto/Gtk
   mkdir blib/lib/auto/Gtk/Gdk
   mkdir blib/lib/auto/Gtk/Gdk/Pixbuf
   usage: chmod [-R [-H | -L | -P]] mode file ...
   *** Error code 1 (ignored)
   Manifying /Gtk::Gdk::Pixbuf::reference.3pm
   sh: cannot create /Gtk::Gdk::Pixbuf::reference.3pm: Permission denied
   Couldn't install /Gtk::Gdk::Pixbuf::reference.3pm

I've determined that the permission and chmod errors are due to
INST_MAN3DIR not being defined in any of the Makefiles.  This causes
chmod to execute as "chmod 755" with no directory argument, as well as
the pod2man process trying to install to $(INST_MAN3DIR)/ which expands
to just ``/''.

I'm not too familiar with Perl's MakeMaker, so I'm not really sure how
to get INST_MAN3DIR defined in each recursive Makefile as each one is
built.  Any ideas?