build: Consistently use 8 hash digits in git describe
build: Consistently use 8 hash digits in git describe

This might otherwise differ between builds depending on branches present
in the repository and the Git version in use (?).

imsodin/syncthing,imsodin/syncthing,imsodin/syncthing,syncthing/syncthing,imsodin/syncthing,imsodin/syncthing,wweich/syncthing,wweich/syncthing,syncthing/syncthing,wweich/syncthing,syncthing/syncthing,syncthing/syncthing,syncthing/syncthing,syncthing/syncthing,wweich/syncthing