[AArch64][PAC][CodeGen] Fix incorrect emitting of DW_AT_LLVM_ptrauth_address_discriminated

The Dwarf attribute `DW_AT_LLVM_ptrauth_address_discriminated` was
emitted for all ptrauth-qualified types, even if the address
discrimination was disabled. This was related to incorrect usage of
`std::optional<bool>` holding the value of the attribute.

Author: kovdan01

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -805,7 +805,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy) {
   if (auto Key = DTy->getPtrAuthKey())
     addUInt(Buffer, dwarf::DW_AT_LLVM_ptrauth_key, dwarf::DW_FORM_data1, *Key);
   if (auto AddrDisc = DTy->isPtrAuthAddressDiscriminated())
-    if (AddrDisc)
+    if (AddrDisc.value())
       addFlag(Buffer, dwarf::DW_AT_LLVM_ptrauth_address_discriminated);
   if (auto Disc = DTy->getPtrAuthExtraDiscriminator())
     addUInt(Buffer, dwarf::DW_AT_LLVM_ptrauth_extra_discriminator,