[CodeGen][SystemZ] Replace PointerType::getUnqual(Type) with opaque version (NFC) (#126280)

Follow-up to #126278

Author: junlarsen

clang/lib/CodeGen/Targets/SystemZ.cpp

@@ -272,7 +272,7 @@ RValue SystemZABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
   SZCGI.handleExternallyVisibleObjABI(Ty.getTypePtr(), CGT.getCGM(),
                                       /*IsParam*/true);
   if (IsIndirect) {
-    DirectTy = llvm::PointerType::getUnqual(DirectTy);
+    DirectTy = llvm::PointerType::getUnqual(DirectTy->getContext());
     UnpaddedSize = DirectAlign = CharUnits::fromQuantity(8);
   } else {
     if (AI.getCoerceToType())