xref to @unnumbered* bug

[Mark Polesky]

I've noticed that cross-references to unnumberedsubsec's
actually link to the section node one level up.  For
example, in
  NR 3.4.3 "Alternative output formats",
clicking on the link to
  "Command line options for lilypond"
sends me to
  Usage 1.2 "Command-line usage".
Then I have to click on the menu link to actually get where
I'm going.

I guess this is a texi2html bug, since the problem doesn't
happen in PDF.

- Mark