[Gptfdisk-general] Support reverting a hybrid MBR configuration

[林博仁 <buo...@gm...>]

(NOTE: I'm not subscribed to this list, please CC me.)

Hello.  I would like to request a feature to revert a previously configured
Hybrid MBR configuration as I like to avoid any *surprises* during
installing Windows.

Thanks!
林博仁 <Buo...@gm...>