[clang][CGObjC] Remove unused ExternalProtocolPtrTy (NFC) (#133870)

This function was previously used to get a type to the protocol that was used to bitcast the initializer of GenerateProtocol. This bitcast has later been removed (thanks to opaque pointers), but the member was left behind. History: - 020de32 used ExternalProtocolPtrTy - 34ee69b removes the bitcast Also technically part of #123569

Author: junlarsen

clang/lib/CodeGen/CGObjCMac.cpp

@@ -184,25 +184,6 @@ class ObjCCommonTypesHelper {
  /// SelectorPtrTy - LLVM type for selector handles (typeof(SEL))
  llvm::PointerType *SelectorPtrTy;
 
-private:
- /// ProtocolPtrTy - LLVM type for external protocol handles
- /// (typeof(Protocol))
- llvm::Type *ExternalProtocolPtrTy;
-
-public:
- llvm::Type *getExternalProtocolPtrTy() {
- if (!ExternalProtocolPtrTy) {
- // FIXME: It would be nice to unify this with the opaque type, so that the
- // IR comes out a bit cleaner.
- CodeGen::CodeGenTypes &Types = CGM.getTypes();
- ASTContext &Ctx = CGM.getContext();
- llvm::Type *T = Types.ConvertType(Ctx.getObjCProtoType());
- ExternalProtocolPtrTy = llvm::PointerType::getUnqual(T);
- }
-
- return ExternalProtocolPtrTy;
- }
-
  // SuperCTy - clang type for struct objc_super.
  QualType SuperCTy;
  // SuperPtrCTy - clang type for struct objc_super *.
@@ -5636,8 +5617,7 @@ CGObjCNonFragileABIMac::CGObjCNonFragileABIMac(CodeGen::CodeGenModule &cgm)
 /* *** */
 
 ObjCCommonTypesHelper::ObjCCommonTypesHelper(CodeGen::CodeGenModule &cgm)
- : VMContext(cgm.getLLVMContext()), CGM(cgm),
- ExternalProtocolPtrTy(nullptr) {
+ : VMContext(cgm.getLLVMContext()), CGM(cgm) {
  CodeGen::CodeGenTypes &Types = CGM.getTypes();
  ASTContext &Ctx = CGM.getContext();
  unsigned ProgramAS = CGM.getDataLayout().getProgramAddressSpace();