bad gcc/libstdc++-v3 build on Solaris 7

[Nathan Myers <ncm at nospam dot cantrip dot org>]

I am trying to build Sunday's CVS gcc-3.1 on Solaris 7.

Configuring with 

  $ ../gcc/configure --with-gnu-ld --with-gnu-as --with-gnu-binutils \
  --with-gcc --enable-languages=c,c++ --prefix=/zembu/ncm/gcc3

as had been recommended, I find that the resulting compiler,
notwithstanding, explicitly calls /usr/ccs/bin/as, ld, etc., regardless
of their place (or presence!) in $PATH.  Looking around, I find that 
its gcc/specs mentions /usr/ccs frequently.  gcc/config/sparc/sol2.h 
and sol2-sld-64.h both mention /usr/ccs pervasively, and seem to make 
no provision for a GNU binutils alternative.

If, as I have been led to believe, the Solaris as and ld are not up to
building libstdc++-v3, what is to be done?

Nathan Myers
ncm at cantrip dot org