fix gamecube progressive detection

[korbosoft]

this makes it match the logic it uses for the wii

[fincs]

Hi, I have a few comments:

• This setting only exists on NTSC (& PAL-M?) GameCubes. On PAL GameCubes there is a 60Hz setting instead. If I understand correctly this change makes PAL GameCubes default to interlaced mode always.
• This setting cannot be set from the GameCube IPL. Commercial games must implement a splash screen on boot to change the setting. The user must therefore own one of these (NTSC only!) games in order to change the setting, without depending on 3rd party tools.
• The only major uses of the digital out port are 1) the official GC component cable, which is rare, and 2) GCVideo-based adapters for use with modern HDMI displays. I think it is unlikely that users want to use either of these in interlaced mode.
• SRAM contents depend on a functional clock battery in order to persist. Replacing the clock battery on a GameCube is a non-trivial process that requires soldering skills. This change therefore introduces annoying behavior on dead-battery GameCubes (such as mine).

[korbosoft]

Hi, I have a few comments:

* This setting only exists on NTSC (& PAL-M?) GameCubes. On PAL GameCubes there is a 60Hz setting instead. If I understand correctly this change makes PAL GameCubes default to interlaced mode always.

* This setting cannot be set from the GameCube IPL. Commercial games [must implement](https://consolemods.org/wiki/GameCube:Games_with_Alternate_Display_Modes) a splash screen on boot to change the setting. The user must therefore own one of these (NTSC only!) games in order to change the setting, without depending on 3rd party tools.

* The only major uses of the digital out port are 1) the official GC component cable, which is rare, and 2) GCVideo-based adapters for use with modern HDMI displays. I think it is unlikely that users want to use either of these in interlaced mode.

* SRAM contents depend on a functional clock battery in order to persist. Replacing the clock battery on a GameCube is a non-trivial process that requires soldering skills. This change therefore introduces annoying behavior on dead-battery GameCubes (such as mine).

good to know