一个关于 Kconfig 和 Makefile 的坑

```make

# Include variables and rules generated by menuconfig

-include $(NPC_HOME)/include/config/auto.conf

-include $(NPC_HOME)/include/config/auto.conf.cmd

# 注意，这些

ifeq ($(CONFIG_WAVEFORM), y)

  VERILATOR_CFLAGS += --trace

endif

```

对CONFIG环境变量的判断一定要放在 -include 后面，否则会无法识别