[clang] [llvm] [AIX] support builtin_cpu_is() for aix (PR #80069)

[Amy Kwan via cfe-commits]

================
@@ -10347,6 +10347,8 @@ def err_x86_builtin_tile_arg_duplicate : Error<
 
 def err_builtin_target_unsupported : Error<
   "builtin is not supported on this target">;
+def err_builtin_aix_os_unsupported : Error<
+  "this builtin is available only in AIX 7.2 and later operating systems">;
----------------
amy-kwan wrote:

```suggestion
  "builtin is available only in AIX 7.2 and later operating systems">;
```

https://github.com/llvm/llvm-project/pull/80069