Have g++ define _FILE_OFFSET_BITS=64 on Solaris

[Jonathan Wakely]

On 21/06/18 16:49 +0200, Rainer Orth wrote:
>Hi Jonathan,
>
>> No objection to this patch, but I'll just note that we have
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81091 suggesting we
>> should use LFS for libstdc++ unconditionally.
>
>seems like a wise move to me.  The libstdc++.so ABI didn't change on
>Solaris either (that possibility had caused concern for me initially);
>didn't check libstdc++fs.a though.

Well the main reason that's only a static library for now is to allow
us to make ABI incompatible changes before we declare it stable and
add those symbols to libstdc++.so forever.