#1648 mk4ht oolatex error and fix

[Josh Granek]

When running "mk4ht oolatex" I got the following error:
Error: Could not find or load main class xtpipes

I tracked down the problem to the file /sw/share/tex4ht/tex4ht.env

I was able to fix this by replacing "%%/sw" with "/sw".

mk4ht is provided by Package tex4ht-20090611-2.