PSA: Default C++ dialect is now C++17

[Martin Liška]

On 6/26/20 9:34 PM, Marek Polacek via Gcc-patches wrote:
> As discussed last month:
> <https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545879.html>
> it's time to change the C++ default to gnu++17.  I've committed the patch after
> testing x86_64-pc-linux-gnu and powerpc64le-unknown-linux-gnu.  Brace yourselves!
> 
> Marek
> 

Just a small note that 510.parest_r SPEC 2017 benchmark can't be built now
with default changed to -std=c++17. The spec config needs to be adjusted.

Martin