[Bug target/95400] -march=native and -march=icelake-client produce different results on icelake client

[crazylht at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95400

--- Comment #5 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Martin Liška from comment #4)
> Can we backport the change to active branches?

Backport to GCC9, GCC10.
Partially backport to GCC8.(drop tremont and tigerlake part).