Revert "tower-frontend: support outputing artifacts into the dep file"
Revert "tower-frontend: support outputing artifacts into the dep file"

This reverts commit d1990f7a884f78c943af918eddf47dcb6f931180.

No idea why lee put this change in there, it broke my artifacts tagging &
therefore wasnt building the vector table properly. anyway, fixed

GaloisInc/tower,GaloisInc/ivory-tower-stm32,GaloisInc/ivory-tower-stm32,GaloisInc/ivory-tower-stm32