Can I ask you why you are trying to compile Linux firmware in VSCode? As the instructions in the README say clearly:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware
For OSPi/OSBO or other Linux-based OpenSprinkler:
https://openthings.freshdesk.com/support/solutions/articles/5000631599
You should use the bulid.sh script to compile it for Linux.