[Ada testsuite] Disable gnat.db/socket1.adb test on Solaris 2

[Arnaud Charlet]

> I've been bitten several times that the 64-bit version of the
> socket1.adb gnat.dg test consumes all available memory on at least
> Solaris 10 and 11, both SPARC and x86.  Often, the machine became
> completely unusable.  I've been unable to further investigate this so
> far: if I run the test standalone, it just SEGVs instead of consuming
> memory.  Therefore, I'd like to disable the test completely on all
> Solaris 2 targets.  Strictly speaking, the problem only exists for
> 64-bit, but I think it would require a .x file to be more selective
> here, provided gnat.dg supports them at all.
>
> Ok for mainline?

Seems fine to me.

Arno