Remove empty DayLengthPreChange

src/settings.cpp

@@ -1839,15 +1839,6 @@ static void ImprovedBreakdownsSettingChanged(int32_t new_value)
 	}
 }
 
-static uint8_t _pre_change_day_length_factor;
-
-static bool DayLengthPreChange(int32_t &new_value)
-{
-	_pre_change_day_length_factor = _settings_game.economy.day_length_factor;
-
-	return true;
-}
-
 static void DayLengthChanged(int32_t new_value)
 {
 	RecalculateStateTicksOffset();

src/table/settings/economy_settings.ini

@@ -10,7 +10,6 @@
 [pre-amble]
 static void TownFoundingChanged(int32_t new_value);
 static void InvalidateCompanyWindow(int32_t new_value);
-static bool DayLengthPreChange(int32_t &new_value);
 static void DayLengthChanged(int32_t new_value);
 static bool CheckSharingRail(int32_t &new_value);
 static void SharingRailChanged(int32_t new_value);
@@ -227,7 +226,6 @@ max      = 125
 str      = STR_CONFIG_SETTING_DAY_LENGTH_FACTOR
 strhelp  = STR_CONFIG_SETTING_DAY_LENGTH_FACTOR_HELPTEXT
 strval   = STR_JUST_COMMA
-pre_cb   = DayLengthPreChange
 post_cb  = DayLengthChanged
 cat      = SC_BASIC
 extver   = SlXvFeatureTest(XSLFTO_AND, XSLFI_VARIABLE_DAY_LENGTH)