This won't work.  gcc needs cc1 in order to build libgcc.a,

That's true.  In fact, I think this is a show-stopper: unless we make
it possible to compile libgcc2.c with whatever C compiler you use to
compile GCC (not easy since it uses GCC features), we can't possibly
support building other languages without C.  We could perhaps make it
work to compile libgcc2.c using C++, if you don't build the C
compiler, but what if you choose to build only Fortran, Pascal or Ada?

But I don't think it is terribly important to make it possible
to build other languages without building C.