[clang] [llvm] Implement a subset of builtin_cpu_supports() features (PR #82809)

[Amy Kwan via cfe-commits]

================
@@ -141,23 +149,30 @@ PPC_LNX_CPU("power10",47)
   #define AIX_BUILTIN_PPC_TRUE 1
   #define AIX_BUILTIN_PPC_FALSE 0
   #define USE_SYS_CONF 2
+  #define SYS_CALL 3
 
   // Supported COMPARE_OP values.
   #define COMP_EQ  0
+  #define COMP_GT 1
+  #define COMP_GE 2
+  #define COMP_NE 3
 
 #endif
 
 // The value of SUPPORT_METHOD can be AIX_BUILTIN_PPC_TRUE,
-// AIX_BUILTIN_PPC_FALSE, or USE_SYS_CONF.
-// When the value of SUPPORT_METHOD is USE_SYS_CONF, the return value
-// depends on the result of comparing the data member of
-// _system_configuration specified by INDEX with a certain value.
+// AIX_BUILTIN_PPC_FALSE, USE_SYS_CONF, API_CALL.
----------------
amy-kwan wrote:

```suggestion
// AIX_BUILTIN_PPC_FALSE, USE_SYS_CONF, or SYS_CALL.
```
I don't see an API_CALL unless I am missing something. Do we mean `SYS_CALL`?

https://github.com/llvm/llvm-project/pull/82809