[PATCH][Ada] Switch gnatbind from C to Ada generation during bootstrap

[Arnaud Charlet]

> As discussed for gcc-in-cxx branch to support Ada one potential issue is
> the compilation of the binder generated C file. A solution is to switch
> the binder to generate Ada, that's what the patch below implements.

This business of doing moves makes me a little nervous. Wouldn't it
be simpler to use a C compiler (e.g. $(CC) -x c or somesuch)?

Also the use of $(MV) -f looks strange, I've never seen this kind of usage
(explicit use of -f) in Makefile before.

So please hold on this patch, and consider compiling b_*.c files using a
C compiler instead, thanks.

Arno