Fix "Joybus host invalid; disabling" warning.

Whenever there is a link connection for GBA, we check if "GBA/LinkHost"
is an empty string. If it is, we send this warning. This is unnecessary
because most connections are assumed to be for localhost, otherwise the
user would set a server ip address and not see this warning.

src/common/ConfigManager.cpp

@@ -517,7 +517,7 @@ void LoadConfig()
 	languageOption = ReadPref("language", 1);
 	linkAuto = ReadPref("LinkAuto", 1);
 	linkHacks = ReadPref("LinkHacks", 0);
-	linkHostAddr = ReadPrefString("LinkHostAddr", "localhost");
+	linkHostAddr = ReadPrefString("LinkHost", "localhost");
 	linkMode = ReadPref("LinkMode", 0); // LINK_DISCONNECTED = 0
 	linkNumPlayers = ReadPref("LinkNumPlayers", 2);
 	linkTimeout = ReadPref("LinkTimeout", 1);

src/wx/opts.cpp

@@ -348,6 +348,8 @@ opts_t::opts_t()
     print_auto_page = true;
     autoPatch = true;
     onlineupdates = 1;
+    // quick fix for issues #48 and #445
+    link_host = "127.0.0.1";
 }
 
 // for binary_search() and friends