diswitch.c: Fix crash issues and and cleanup

- Partial rewrite to clean up dipswitch struct to prevent potential crashes
- Fix problems on vs games without dipswitch to cause core to crash
- Create dipswitch struct based on new core options layout

src/drivers/libretro/dipswitch.h

@@ -3,8 +3,9 @@
 
 #include <libretro.h>
 
-void set_dipswitch_variables(unsigned *index, struct retro_core_option_definition *vars);
+size_t set_dipswitch_variables(unsigned current_index, struct retro_core_option_definition *vars);
 void update_dipswitch(void);
+void DPSW_Cleanup(void);
 
 extern retro_environment_t environ_cb;
 

src/drivers/libretro/libretro.c

@@ -759,7 +759,8 @@ static void set_variables(void)
    }
 
    /* Append dipswitch settings to core options if available */
-   set_dipswitch_variables(&index, option_defs_us);
+   index += set_dipswitch_variables(index, option_defs_us);
+   option_defs_us[index] = option_defs_empty;
 
    libretro_set_core_options(environ_cb);
 }
@@ -987,6 +988,7 @@ void retro_deinit (void)
    ps2 = NULL;
 #endif
    libretro_supports_bitmasks = false;
+   DPSW_Cleanup();
 }
 
 void retro_reset(void)