undefined reference to lang_specific_driver

[Ellery Newcomer]

Hey all.

trying to build gdc with gcc 4.7 in release mode 
(--enable-checking=release, and no --disable-bootstrap, per the general 
instructions), and I'm getting

gcc.o: In function `process_command(unsigned int, cl_decoded_option*)':
gcc.c:(.text+0x2f60): undefined reference to 
`lang_specific_driver(cl_decoded_option**, unsigned int*, int*)'

Anyone know off the top of their heads what this might be about? I'm 
pretty sure this didn't happen when using  --disable-bootstrap 
--enable-checking=yes.