[clang] [libc] [llvm] Reapply "[AMDGPU] Use COV6 by default (#118515)" (PR #130963)

[Joseph Huber via llvm-commits]

================
@@ -332,6 +332,8 @@ Target Specific Changes
 AMDGPU Support
 ^^^^^^^^^^^^^^
 
+- Bump the default code object version to 6. ROCm 6.3 is required to run any program compiled with COV6.
----------------
jhuber6 wrote:

Is it really? What runtime changes actually were required. Figured it'd still work so long as you're not using the generic targets.

https://github.com/llvm/llvm-project/pull/130963