[Ada] Bootstrapping mainline GNAT fails

[Richard Kenner]

  - Bootstrapping with CC=gcc-3.0 does NOT work on Debian/x86 unstable.

  - Bootstrapping with CC=gcc (2.95.4 20011002 (Debian prerelease))
    does NOT work either.

This seems reasonable.  There was no reliable GNAT based on GCC 3.0 or
2.95 until now.