Add RegisterCodeGenFlags to get full codegen flags list

Author: ldm0

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -9,6 +9,7 @@
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/CommandFlags.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/AssemblyAnnotationWriter.h"
@@ -50,6 +51,8 @@
 
 using namespace llvm;
 
+static codegen::RegisterCodeGenFlags CGF;
+
 typedef struct LLVMOpaquePass *LLVMPassRef;
 typedef struct LLVMOpaqueTargetMachine *LLVMTargetMachineRef;