Further enhancements for building Japanese PDF

* Use command string to replace fop-ttfreader if it's not available
  and fop is installed in /usr/share/java
* If neither is available, disregard the japanese font configure settings
  and use the defaults because we can't get the metrics
* If using a default font, copy its metric file to guide/ja so that the
  user doesn't have to.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash-docs/trunk@23695 57a11ea4-9604-0410-9ed3-97b8803252fd