Fix keycode_to_keyname return value

src/keycode.cpp

@@ -206,7 +206,7 @@ static const char *KeyNames[] =
 		"-", "-", "-", "-", "-", "-", "-", "-", "Attn", "CrSel", "ExSel",
 		"Erase OEF", "Play", "Zoom", "PA1", "OEM Clear", "-" };
 
-const std::string &keycode_to_keyname(s32 keycode)
+const char *keycode_to_keyname(s32 keycode)
 {
 	return KeyNames[keycode];
 }

src/keycode.h

@@ -24,7 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <string>
 
 irr::EKEY_CODE keyname_to_keycode(const char *name);
-const std::string &keycode_to_keyname(s32 keycode);
+const char *keycode_to_keyname(s32 keycode);
 
 // Key configuration getter
 irr::EKEY_CODE getKeySetting(const char *settingname);