[NFC] Add missing includes for LLVM_ENABLE_MODULES builds

Building LLVM with the LLVM_ENABLE_MODULES cmake option fails when the modules are being compiled due to missing includes. This is a side effect of some transitive includes that changed recently.

Differential Revision: https://reviews.llvm.org/D103645

llvm/include/llvm/CodeGen/MBFIWrapper.h

@@ -15,6 +15,7 @@
 #define LLVM_CODEGEN_MBFIWRAPPER_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/Support/BlockFrequency.h"
 
 namespace llvm {

llvm/include/llvm/Support/CFGUpdate.h

@@ -14,6 +14,7 @@
 #ifndef LLVM_SUPPORT_CFGUPDATE_H
 #define LLVM_SUPPORT_CFGUPDATE_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Support/Compiler.h"