scons: Reverts LTO for opt, perf and prof builds.

This reverts
https://gem5-review.googlesource.com/c/public/gem5/+/40815
and adds the `--with-lto` to enable LTO; and removes `--no-lto`.

Change-Id: I7dbd2b555570c90c98f38c7c02eb052571f7b6bd
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/44886
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45839
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
1 file changed