compiler/commands: make gitHash settable at compile-time. (#14654)
compiler/commands: make gitHash settable at compile-time. (#14654)

This is useful for building nightlies, since we will be building from a
generated source archive and git metadata is lost there.
dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim,dom96/Nim