This fixes a nasty issue where you can change the Dual Core setting
during emulation, if it has been overridden by GameINI or NetPlay, by
simply changing any of the non-disabled settings. This is because
changing any of the settings will write all of them to the config.
This issue is particularly nasty because managing to disable Dual Core
during emulation, and then stopping it, results in the emulator core
being totally deadlocked. It's impossible to recover from this state,
and Dolphin will remain as a zombie process on the system, consuming
resources and holding locks, until forcibly killed.
a33593baf7