[NFC] Fic clangIR build after #158679

The commit from #158679 added getStaticTripCount to LoopLikeOpInterface,
which the CIRLoopOpInterface uses.  However, it doesn't include APInt.

This patch adds an include for APInt to CIRLoopOpInterface, plus a
'using', as we're likely to run into this again.

Author: erichkeane

clang/include/clang/CIR/Interfaces/CIRLoopOpInterface.h

@@ -13,12 +13,14 @@
 #ifndef CLANG_CIR_INTERFACES_CIRLOOPOPINTERFACE_H
 #define CLANG_CIR_INTERFACES_CIRLOOPOPINTERFACE_H
 
+#include "llvm/ADT/APInt.h"
 #include "mlir/IR/BuiltinTypes.h"
 #include "mlir/IR/OpDefinition.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/Interfaces/ControlFlowInterfaces.h"
 #include "mlir/Interfaces/LoopLikeInterface.h"
 
+using llvm::APInt;
 namespace cir {
 namespace detail {