pc_lpt_device does not allow for internal Centronics default slot handling

[angelosa]

https://github.com/mamedev/mame/blob/ddbdbb3a616a704a9d0bb43731e424b2bf98ba2b/src/devices/machine/pc_lpt.cpp#L49

There's currently no way to override pc_lpt_device with arbitrary internal slots, required by Arcade games such as atari/mediagx.cpp and misc/neomania.cpp.

There are two courses of action that I see here:

1. Make the pc_lpt_device to have an optional extra argument at constructor time for the default tag, move the declaration to centronics_devices anyway (as device.option_add_internal ?).
2. Make getter virtuals for centronics_devices and the default option tag, making the overrides local to the driver.

[ajrhacker]

Of the two, I'd much prefer option 1. In principle, I think that interface devices should be decoupled from the peripheral connector slots that they normally control as much as is practical.

[cuavas]

Option 1 should be fine for now.

The Centronics port device itself has design issues, but that’s a bigger issue to deal with.