(Settings data/iOS) Fix crash at startup with new config - audio latency was being set to
0 because g_defaults.out_latency would point to 0 - instead, we check
if g_defaults.settings.out_latency is higher than 0 and if so, set the
setting to that - otherwise, default to value in config.def.h

On an unrelated note - the setting I just added to settings_data.c still
doesn't show up. This code is in need of some serious refactoring