[clang] [ARM64EC] Fix compilation of intrin.h in ARM64EC mode. (PR #87717)

[Freddy Ye via cfe-commits]

================
@@ -44,7 +44,7 @@ unsigned char _InterlockedCompareExchange128_rel(__int64 volatile *_Destination,
                                                  __int64 *_ComparandResult);
 #endif
 
-#ifdef __x86_64__
+#ifdef __x86_64__ && !defined(__arm64ec__)
----------------
FreddyLeaf wrote:

Hello, we found compile errors on this line:
```
(47,19): error: extra tokens at end of #ifdef directive [-Werror,-Wextra-tokens]
```
Seems like this line forgot to change #ifdef when changed into expression


https://github.com/llvm/llvm-project/pull/87717