patch for -Wno-long-long and early GNAT compilers

[Richard Kenner]

    I can make arguments either way, but consider that there's
    considerable time and effort been expended verifying that 2.95 and 3.0
    compile the back end correctly, on a wide variety of architectures.
    2.8.1, on the other hand, has not received much attention at all, and
    is known to have problems on some architectures.  So I think a patch
    which allows people to continue using 2.95 or 3.0 for everything but
    Ada is safer than a patch which forces everything to get built with
    2.8.1.

I disagree because you are adding extra complexity to an already complex
process.  Having one compiler run autoconf and another do the actual
compilations is asking for trouble, for example.