[clang] clang/AMDGPU: Restore O3 checks in default-attributes.hip (PR #115238)

[Tom Weaver via cfe-commits]

TomWeaver18 wrote:

Hello and greetings from the UK.

My apologies but I've had to revert this change as it has turned several build-bots red for a good many hours this morning.

https://lab.llvm.org/buildbot/#/builders/144/builds/11132
https://lab.llvm.org/buildbot/#/builders/46/builds/7541
https://lab.llvm.org/buildbot/#/builders/190/builds/9077

The revert is in the following commit: 4bcd4d843f660c1a435159a2964f0c4cf4564ab1

Warmest regards,
Tom W!

https://github.com/llvm/llvm-project/pull/115238