Fixed commands in Makefile

Makefile

@@ -3,15 +3,23 @@
 SRC = $(wildcard src/*.cpp)
 OBJ = $(patsubst src/%.cpp,build/%.o,$(SRC))
 
+# Detect Windows
+ifeq ($(OS),Windows_NT)
+    MKDIR = if not exist build mkdir build
+    RM = rmdir /s /q build & del /q mcc.exe
+else
+    MKDIR = mkdir -p build
+    RM = rm -rf build mcc
+endif
+
 all: mcc
 
 mcc: $(OBJ)
 	g++ $(OBJ) -o mcc -lpthread -lws2_32
 
 build/%.o: src/%.cpp
-	mkdir -p build
+	$(MKDIR)
 	g++ -c $< -o $@
 
 clean:
-	rm -rf build
-	rm -f mcc.exe mcc
+	$(RM)