[Frontend] Remove unused includes (NFC) (#116927)

Identified with misc-include-cleaner.

llvm/lib/Frontend/Atomic/Atomic.cpp

@@ -8,11 +8,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Frontend/Atomic/Atomic.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/Frontend/Atomic/Atomic.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/Operator.h"
 
 namespace {} // namespace
 

llvm/lib/Frontend/HLSL/HLSLResource.cpp

@@ -13,7 +13,6 @@
 #include "llvm/Frontend/HLSL/HLSLResource.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/IR/Module.h"
 
 using namespace llvm;
 using namespace llvm::hlsl;

llvm/lib/Frontend/Offloading/Utility.cpp

@@ -16,7 +16,6 @@
 #include "llvm/IR/Value.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/MemoryBufferRef.h"
-#include "llvm/Support/YAMLTraits.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 
 using namespace llvm;

llvm/lib/Frontend/OpenACC/ACC.cpp

@@ -8,9 +8,7 @@
 
 #include "llvm/Frontend/OpenACC/ACC.h.inc"
 
-#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
-#include "llvm/Support/ErrorHandling.h"
 
 using namespace llvm;
 using namespace acc;

llvm/lib/Frontend/OpenMP/OMP.cpp

@@ -9,15 +9,11 @@
 #include "llvm/Frontend/OpenMP/OMP.h"
 
 #include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/StringSwitch.h"
 #include "llvm/Demangle/Demangle.h"
 #include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/StringSaver.h"
 
 #include <algorithm>
 #include <cstdio>

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -59,7 +59,6 @@
 
 #include <cstdint>
 #include <optional>
-#include <stack>
 
 #define DEBUG_TYPE "openmp-ir-builder"