[clang] [CIR] Support x86 encodeKey builtins (PR #179308)

[Andy Kaylor via cfe-commits]

================
@@ -15,17 +15,29 @@
 #include "CIRGenFunction.h"
 #include "CIRGenModule.h"
 #include "mlir/IR/Attributes.h"
+#include "mlir/IR/Builders.h"
----------------
andykaylor wrote:

That is the common practice in LLVM, I believe.

https://llvm.org/docs/CodingStandards.html#include-as-little-as-possible

Including something explicitly that has already been included elsewhere doesn't introduce any significant overhead, but if the code that uses it is later removed, the explicit include is likely to be left behind, so in general I think it's good practice not to introduce new includes unless you need to do so.

https://github.com/llvm/llvm-project/pull/179308