[Bug target/78994] -Ofast makes aarch64 C++ benchmark slower for A53

[tulipawn at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78994

--- Comment #7 from PeteVine <tulipawn at gmail dot com> ---
Not affected by -mno-fix-cortex-a53-843419 which gives the issue full validity.
-Ofast pessimizes Cortex A53 codegen somehow and switching to e.g.
-mcpu=cortex-a57 fixes it. (tested on trunk)