RFC/Ada: removal of $(ADAC) support

[Richard Kenner]

    The difference is that major Linux distributors, and all three of the
    *BSDs, deliberately shipped a 2.95 "gcc" but a 2.8 "gnatgcc".
    Precisely because of (1).  That's enough evidence as far as I care.

That's not my understanding.  They shipped a "2.95" gcc because they wanted
"the latest and greatest" gcc.  But there was no GNAT for 2.95 so they had no
choice but to distribute one based on 2.8 since they wanted GNAT there.

I have seen no evidence that "gnatgcc" can't bootstrap GCC 3.x and indeed
have seen plenty of evidence that it can.