[clang] [clang] Separate Intel ADC instrinsics from ADX intrinsics (PR #75992)

[Phoebe Wang via cfe-commits]

================
@@ -580,8 +580,7 @@ _storebe_i64(void * __P, long long __D) {
 #include <cetintrin.h>
 #endif
 
-/* Some intrinsics inside adxintrin.h are available only on processors with ADX,
- * whereas others are also available at all times. */
----------------
phoebewang wrote:

Sorry, just noticed this. Since we removed the comments, should we use the same format for `adxintrin.h` and add comment for `adcintrin.h`, e.g., 

```
/* Intrinsics inside adcintrin.h are available at all times. */
#include <adcintrin.h>

#if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
    defined(__ADX__)
#include <adxintrin.h>
#endif
```

https://github.com/llvm/llvm-project/pull/75992