build machinery TODO (was: Testsuite and Fortran)

[Joe Buck]

> 
> > note that check-c++ may actually be the g++ + libstdc++-v3 rule.
> ...
> If the concensus was that it should test both, then go ahead and
> change the check-c++ alias rule I put in.

I agree that c++ checking should run both the g++ and the libstdc++ tests.
Without a working library, you don't have a working C++, and libstdc++
fails have often revealed problems in the compiler.