Add flake.nix

Makefile

@@ -23,9 +23,9 @@ SDL_LIBS_RELEASE := $(shell pkg-config --libs sdl3 sdl3-ttf sdl3-image)
 
 CFLAGS_DEBUG := \
 	-std=c++20 -Wall -Wextra \
-	-O0 -g -fno-omit-frame-pointer \
+	-Og -g -fno-omit-frame-pointer \
 	-Wno-unused-command-line-argument \
-	-I./include -I./libs/mruby/include \
+	-I./include -I./libs/mruby/build/host/include \
 	$(SDL_CFLAGS)
 
 CFLAGS_RELEASE := \
@@ -33,7 +33,7 @@ CFLAGS_RELEASE := \
 	-flto=thin \
 	-fno-rtti -fomit-frame-pointer -DNDEBUG -s \
 	-Wno-unused-command-line-argument \
-	-I./include -I./libs/mruby/include \
+	-I./include -I./libs/mruby/build/host/include \
 	$(SDL_CFLAGS)
 
 PCH_CFLAGS_DEBUG := $(CFLAGS_DEBUG) -x c++-header
@@ -123,4 +123,4 @@ $(OBJ_DIR)/release/%.o: $(SRC_DIR)/%.cc $(PCH_RELEASE)
 clean:
 	@rm -rf $(OBJ_DIR) $(BIN_DIR)
 	@$(MGEM_DIR)/compile.sh clean
-	@echo "Cleaned build artifacts."
+	@echo "Cleaned build artifacts."