ports/60391: [SW-BUG] Fix hpijs to work with CUPS

[John Merryweather Cooper]

Is there any interest in committing/approving this patch?  With it, I 
have driver support under CUPS for my HP DeskJet 5550.  Without it, 
print/hpijs is useless with CUPS installed.

If print/hpijs must be kept "pure" from CUPS/X11, I'd be happy to 
creat/maintain a print/hpijs-cups port.

jmc