MacOS - Bug App crashes when opening Preferences dialog

[palmerj]

trafficstars

In the current master version (a0c7dd7) of the MacOS build, when I try to load up the Preferences dialog the application seg faults. I've tracked this down to nBurnDrvActive still being set to its initialised value when the following code is executed: https://github.com/finalburnneo/FBNeo/blob/master/src/burn/burn.cpp#L310.

I was running a debug release built with xcode 12.5.1, running on MacOS 11.6 Big Sur.

\cc @0xe1f

[0xe1f]

The version in master is not stable, and it wouldn't surprise me if it crashed - I have not yet completed input configuration.