Add a cache buster value to Windows LLVM lib fingerprint
Add a cache buster value to Windows LLVM lib fingerprint

The addition of a value allows us to bust the cache for other reasons
we might need like:

- cache is corrupted
- builder image changed
- we are feeling frisky

jemc/ponyc,dipinhora/ponyc,sgebbie/ponyc,ponylang/ponyc,dipinhora/ponyc,sgebbie/ponyc,dipinhora/ponyc,sgebbie/ponyc,jemc/ponyc,jemc/ponyc,sgebbie/ponyc,ponylang/ponyc,sgebbie/ponyc,ponylang/ponyc