Add external borderless helper

Signed-off-by: Sean Du <do4suki@gmail.com>

Makefile

@@ -1,4 +1,5 @@
 TARGET := build/version.dll
+HELPER_TARGET := build/cgss-borderless-helper.exe
 BUILD_DIR := build
 OBJ_DIR := $(BUILD_DIR)/obj
 BUILD ?= release
@@ -14,6 +15,8 @@ CFLAGS := -std=gnu11 $(DEFINES) $(INCLUDES)
 CXXFLAGS := -std=gnu++20 -fno-exceptions -fno-rtti $(DEFINES) $(INCLUDES)
 LDFLAGS := -shared -static-libgcc -static-libstdc++
 LDLIBS := -luser32 -lkernel32
+HELPER_LDFLAGS := -static-libgcc -static-libstdc++ -mwindows
+HELPER_LDLIBS := -luser32 -lkernel32 -lshell32
 
 ifeq ($(BUILD),debug)
   DEFINES += -D_DEBUG
@@ -38,18 +41,22 @@ CXX_SRCS := \
 	src/config.cpp \
 	src/il2cpp_symbols.cpp
 
+HELPER_CXX_SRCS := \
+	src/helper_main.cpp
+
 RC_SRCS := src/version.rc
 DEF_FILE := src/version.def
 
 C_OBJS := $(patsubst %.c,$(OBJ_DIR)/%.o,$(C_SRCS))
 CXX_OBJS := $(patsubst %.cpp,$(OBJ_DIR)/%.o,$(CXX_SRCS))
+HELPER_CXX_OBJS := $(patsubst %.cpp,$(OBJ_DIR)/%.o,$(HELPER_CXX_SRCS))
 RC_OBJS := $(patsubst %.rc,$(OBJ_DIR)/%.res,$(RC_SRCS))
 OBJS := $(C_OBJS) $(CXX_OBJS) $(RC_OBJS)
 
 .PHONY: all release debug clean
 
-all: $(TARGET)
-release: $(TARGET)
+all: $(TARGET) $(HELPER_TARGET)
+release: $(TARGET) $(HELPER_TARGET)
 debug:
 	$(MAKE) BUILD=debug
 
@@ -57,6 +64,10 @@ $(TARGET): $(OBJS) $(DEF_FILE)
 	@mkdir -p $(dir $@)
 	$(CXX) $(LDFLAGS) -o $@ $(OBJS) $(DEF_FILE) $(LDLIBS)
 
+$(HELPER_TARGET): $(HELPER_CXX_OBJS)
+	@mkdir -p $(dir $@)
+	$(CXX) $(HELPER_LDFLAGS) -o $@ $(HELPER_CXX_OBJS) $(HELPER_LDLIBS)
+
 $(OBJ_DIR)/%.o: %.c
 	@mkdir -p $(dir $@)
 	$(CC) $(CFLAGS) -c $< -o $@