[clang] [CIR] Upstream X86 builtin _mm_prefetch and _mm_clflush (PR #167401)

[Andy Kaylor via cfe-commits]

================
@@ -43,11 +85,28 @@ mlir::Value CIRGenFunction::emitX86BuiltinExpr(unsigned builtinID,
   // Find out if any arguments are required to be integer constant expressions.
   assert(!cir::MissingFeatures::handleBuiltinICEArguments());
 
+  // The operands of the builtin call
+  llvm::SmallVector<mlir::Value, 4> ops;
+
+  // `ICEArguments` is a bitmap indicating whether the argument at the i-th bit
+  // is required to be a constant integer expression.
+  unsigned ICEArguments = 0;
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andykaylor wrote:

```suggestion
  unsigned iceArguments = 0;
```
Even though this is an acronym, our coding standards expect lowercase to start the name.

https://github.com/llvm/llvm-project/pull/167401