Properly handle 'Cart.StartBank' set to 'AUTO' in the ROM properties.

src/emucore/Console.cxx

@@ -119,7 +119,8 @@ Console::Console(OSystem& osystem, unique_ptr<Cartridge>& cart,
   // Let the cart know how to query for the 'Cartridge.StartBank' property
   myCart->setStartBankFromPropsFunc([this]() {
     const string& startbank = myProperties.get(PropType::Cart_StartBank);
-    return startbank == EmptyString ? -1 : atoi(startbank.c_str());
+    return (startbank == EmptyString || BSPF::equalsIgnoreCase(startbank, "AUTO"))
+        ? -1 : atoi(startbank.c_str());
   });
 
   // We can only initialize after all the devices/components have been created

src/emucore/Props.cxx

@@ -314,7 +314,7 @@ string Properties::ourDefaultProperties[static_cast<uInt8>(PropType::NumTypes)]
   "",       // Cart.Note
   "",       // Cart.Rarity
   "MONO",   // Cart.Sound
-  "",       // Cart.StartBank
+  "AUTO",   // Cart.StartBank
   "AUTO",   // Cart.Type
   "B",      // Console.LeftDiff
   "B",      // Console.RightDiff