Make frame counter unsigned when it is used in calculations

Otherwise the arrays will index out of bounds when the frame counter overflows.

Discovered via the YNOOnline project were savegames that are used for multiple years can happen :)

Author: Ghabry

src/scene_battle_rpg2k3.cpp

@@ -421,7 +421,7 @@ void Scene_Battle_Rpg2k3::UpdateAnimations() {
 		}
 	}
 
-	auto frame_counter = Main_Data::game_system->GetFrameCounter();
+	auto frame_counter = static_cast<uint32_t>(Main_Data::game_system->GetFrameCounter());
 
 	bool ally_set = false;
 	if (status_window->GetActive()

src/tilemap_layer.cpp

@@ -143,7 +143,7 @@ static constexpr uint8_t BlockD_Subtiles_IDS[50][2][2][2] = {
 // Set of neighboring autotiles -> autotile variant
 // Each neighbor is represented by a single bit (1 - same autotile, 0 - any other case)
 // The bits are ordered as follows (from most to least significant bit): NW N NE W E SW S SE
-static const std::unordered_map<uint8_t, int> AUTOTILE_D_VARIANTS_MAP = { //it also works with A 
+static const std::unordered_map<uint8_t, int> AUTOTILE_D_VARIANTS_MAP = { //it also works with A
 	{0b11111111, 0},
 	{0b01111111, 1},
 	{0b11011111, 2},
@@ -285,7 +285,7 @@ void TilemapLayer::Draw(Bitmap& dst, uint8_t z_order, int render_ox, int render_
 	};
 
 	// FIXME: When Game_Map singleton is made an object we can remove this null check
-	const auto frames = Main_Data::game_system ? Main_Data::game_system->GetFrameCounter() : 0;
+	const auto frames = Main_Data::game_system ? static_cast<uint32_t>(Main_Data::game_system->GetFrameCounter()) : 0u;
 	auto animation_step_c = (frames / 6) % 4;
 	auto animation_step_ab = frames / animation_speed;
 	if (animation_type) {