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

[Richard Kenner]

    When raise.c is compiled by 2.8.1, it refers to __dummy.  That symbol
    was removed from libgcc.a in 3.0, so if ADAC is 2.8.1 and CC is 3.0,
    unless we provide a definition, the link will fail.

Why do we want to support a different CC than ADAC?   Why not just
use CC for everything and choose a CC that can compile Ada?  I think we're
starting to go to a lot of trouble to support something that doesn't seem
to gain us anything except the potential for more trouble.

    The install.texi change just adds "and the matching @file{cc1}" right
    after "@file{gnat1}"; this is not obvious because the paragraph got
    re-wrapped.

Right, the doc change is fine.