textproc/bibtex2html: Mark BROKEN with PDFDOCS

• Fails to build with PDFDOCS option:

pdfTeX error: pdflatex (file cm-super-t1.enc): cannot open encoding file for r

• Remove PORTDOCS as PORTDOCS has no value without DOCS option
• Pet portclippy while I am here

Approved by: portmgr (blanket)
Sponsored by: Nepustil