[Bug pch/71934] pch cannot be disabled so gcc cannot be position independent

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71934

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Actually you could exactly what is done for darwin targets to get it working on
PIE.

Also what do you mean by disabled?  Do you mean not doing a PCH for libstdc++
(there is already an option for that; can't remember offhand) or mean execute a
sorry for when someone tries it.  As I said there is a way to do PCH even with
PIE using mmap early on.