dcnet: libretro support

shell/libretro/libretro_core_options.h

@@ -245,6 +245,20 @@ struct retro_core_option_v2_definition option_defs_us[] = {
       },
       "enabled",
    },
+   {
+      CORE_OPTION_NAME "_dcnet",
+      "Use DCNet (Experimental)",
+      NULL,
+      "Connect to the experimental DCNet cloud service.",
+      NULL,
+      "system",
+      {
+         { "disabled", NULL },
+         { "enabled",  NULL },
+         { NULL, NULL },
+      },
+      "disabled",
+   },
 
    {
       CORE_OPTION_NAME "_internal_resolution",

shell/libretro/option.cpp

@@ -122,6 +122,7 @@ Option<int> GGPOAnalogAxes("", 0);
 Option<bool> NetworkOutput(CORE_OPTION_NAME "_network_output", false);
 Option<int> MultiboardSlaves("", 0);
 Option<bool> BattleCableEnable("", false);
+Option<bool> UseDCNet(CORE_OPTION_NAME "_dcnet", false);
 
 // Maple