src/gnu/dist/gcc incomplete? or what?

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

I wanted to build gcj, the gcc java compiler, to compile java to
bytecode.  So I went to one of my 3.1 machines, created a sandbox
directory /home/mouse/gcj for the purpose, symlinked src to
/usr/src/gnu/dist/gcc, created subdirs INST and OBJDIR, and ran

% sh src/configure --prefix=/home/mouse/gcj/INST 
--with-local-prefix=/home/mouse/gcj/INST --disable-shared 
--enable-threads=single --enable-languages=java --disable-libgcj

and it chugged along for a while and fell over, ending with

checking assembler --gstabs support... yes
checking linker read-only and read-write section mixing... read-write
checking linker PT_GNU_EH_FRAME support... yes
configure: error: 
The following requested languages were not found: java
The following languages were available: c c++ f77 objc treelang
Configure in /home/mouse/gcj/gcc failed, exiting.
[Omega] 3> 

But the docs in that same tree indicate that java is a supported
language.  Is the NetBSD import of gcc incomplete, or did I do
something wrong, or is java support busted in this version of gcc, or
what?  It seems unlikely that the import is incomplete, both because
that would run counter to the whole idea of importing vendor
distributions and because treelang (which I don't think we build) _is_
listed.  But _something_ certainly didn't work.

Of course, it's possible that nobody here knows; it's not as if gcj is
one of the things NetBSD supports building from the shipped sources.
But it's also possible that someone will say "oh, yes, we didn't import
$SOMEDIR because we don't need it for anything we build" or some such,
which is really why I'm asking here first.

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