iidx,sdvx: detect SuperstepSound init failures and log a message upon crash (#376)

## Link to GitHub Issue, if one exists
#345 

## Description of change
If we see SuperstepSound failure during boot, remember it, and when the
game eventually crashes, log a series of warning messages to surface why
the game likely failed to launch.

## Testing
Tested both iidx and sdvx with an audio device set to not allow
exclusive mode.

src/spice2x/launcher/signal.h

@@ -5,6 +5,7 @@ namespace launcher::signal {
     // settings
     extern bool DISABLE;
     extern bool USE_VEH_WORKAROUND;
+    extern bool SUPERSTEP_SOUND_ERROR;
 
     //void print_stacktrace();
     void attach();