[Bug c++/64142] Add option, -felide-copies

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64142

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
C++17 changes the rules about elide-copies and actually forces to do it rather
than just allowing it.