Remove unnecessary forward declarations. NFCI.

All of these forward declarations are fully defined in headers that are directly included.

Author: RKSimon

llvm/include/llvm/DebugInfo/PDB/PDBSymbol.h

@@ -42,7 +42,6 @@ class StringRef;
 class raw_ostream;
 
 namespace pdb {
-class IPDBRawSymbol;
 class IPDBSession;
 
 #define DECLARE_PDB_SYMBOL_CONCRETE_TYPE(TagValue)                             \

llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h

@@ -28,8 +28,6 @@ class TargetMachine;
 
 namespace orc {
 
-class JITTargetMachineBuilder;
-
 IRSymbolMapper::ManglingOptions
 irManglingOptionsFromTargetOptions(const TargetOptions &Opts);
 

llvm/include/llvm/ExecutionEngine/Orc/GlobalMappingLayer.h

@@ -22,7 +22,6 @@
 namespace llvm {
 
 class Module;
-class JITSymbolResolver;
 
 namespace orc {
 

llvm/include/llvm/IR/LegacyPassManagers.h

@@ -88,7 +88,6 @@
 namespace llvm {
 template <typename T> class ArrayRef;
 class Module;
-class Pass;
 class StringRef;
 class Value;
 class Timer;

llvm/include/llvm/MC/MCELFObjectWriter.h

@@ -23,7 +23,6 @@ namespace llvm {
 class MCAssembler;
 class MCContext;
 class MCFixup;
-class MCObjectWriter;
 class MCSymbol;
 class MCSymbolELF;
 class MCValue;

llvm/include/llvm/MC/MCParser/MCTargetAsmParser.h

@@ -24,7 +24,6 @@
 namespace llvm {
 
 class MCInst;
-class MCParsedAsmOperand;
 class MCStreamer;
 class MCSubtargetInfo;
 template <typename T> class SmallVectorImpl;

llvm/include/llvm/ProfileData/SampleProf.h

@@ -37,8 +37,6 @@
 
 namespace llvm {
 
-class raw_ostream;
-
 const std::error_category &sampleprof_category();
 
 enum class sampleprof_error {

llvm/include/llvm/Transforms/Utils/LoopUtils.h

@@ -39,7 +39,6 @@ class ScalarEvolution;
 class SCEV;
 class SCEVExpander;
 class TargetLibraryInfo;
-class TargetTransformInfo;
 class LPPassManager;
 class Instruction;
 struct RuntimeCheckingPtrGroup;

llvm/include/llvm/Transforms/Utils/LoopVersioning.h

@@ -25,7 +25,6 @@ namespace llvm {
 class Loop;
 class LoopAccessInfo;
 class LoopInfo;
-class ScalarEvolution;
 struct RuntimeCheckingPtrGroup;
 typedef std::pair<const RuntimeCheckingPtrGroup *,
                   const RuntimeCheckingPtrGroup *>