Further cleanup on "make test"

[Quuxplusone]

commit ea5b3df8fc83b2d73bf17be99b3daa4086df3c70

    Remove extraneous space at the end of the function parameter list

commit d9d938bf70bc37fcd15154d8927a7e77bf2fbc6b

    Further clean up 'make test'
    
    Use the same input file for both C and C++.
    Verify that `cdecl` gives warnings on C++ constructs.
    Add fflush in cdecl.c so that the warnings on stderr will come out
    properly interleaved with the ordinary output on stdout, for the
    benefit of the tests.
    Fix up ALLFILES (which had gotten out of sync), not that I think it's
    really necessary anymore anyway.