build/applications/main.o: In function `usbd_cdc_start':
main.c:(.text.usbd_cdc_start+0x4): undefined reference to `cdc_acm_init'
build/applications/main.o: In function `usbd_cdc_send':
main.c:(.text.usbd_cdc_send+0x4): undefined reference to `cdc_acm_data_send_with_dtr_test'
build/applications/main.o: In function `usbh_start':
main.c:(.text.usbh_start+0x4): undefined reference to `usbh_initialize'
大佬，github上源码编译不过，麻烦指教下，谢谢