port kmalloc and printk to rust (#83)

* 暂时移除cbindgen

* 将lib文件夹更名为libs文件夹（解决rust的冲突）

* 实现了全局的allocator

* 实现了printk宏

* new: 完善了printk的颜色

kernel/src/libs/Makefile

@@ -0,0 +1,19 @@
+
+CFLAGS += -I .
+
+kernel_lib_subdirs:= libUI sys libELF rust_helloworld
+
+kernel_lib_objs:= $(shell find ./*.c)
+
+ECHO:
+	@echo "$@"
+
+$(kernel_lib_subdirs): ECHO
+	$(MAKE) -C $@ all CFLAGS="$(CFLAGS)" ASFLAGS="$(ASFLAGS)" PIC="$(PIC)"
+
+$(kernel_lib_objs): ECHO
+	$(CC) $(CFLAGS) -c $@ -o $@.o
+
+all: $(kernel_lib_objs) $(kernel_lib_subdirs)
+	@echo $(kernel_lib_objs)
+