Fix checkout bug

Makefile

@@ -1,4 +1,6 @@
 SRC := $(wildcard src/*.c)
+OBJ := $(addsuffix .o, $(basename $(SRC)))
+OBJ_DEST := $(addprefix build/, $(OBJ))
 CFLAGS := -lcrypto -lm -lz
 
 DEBUG ?= false
@@ -6,8 +8,15 @@ ifeq ($(DEBUG), true)
 	DEBUG_FLAG = -DDEBUG -ggdb
 endif
 
-all: $(SRC)
-	gcc -o build/cgit $(SRC) $(CFLAGS) $(DEBUG_FLAG)
+all: $(OBJ_DEST)
+	gcc -o build/cgit $(OBJ_DEST) $(CFLAGS) $(DEBUG_FLAG)
+
+build/%.o: %.c
+	@mkdir -p $(dir $@)
+	gcc -c $< -o $@ $(CFLAGS) $(DEBUG_FLAG)
+
+clean:
+	@rm -rf build/*
 
 run: all
 	build/cgit