Fix bundle hashing.

[ry]

Across several PRs we are experiencing AppVeyor failure. It appears to be due to the bundle not rebuilding... I believe this fixes it.

Examples of the failures we're seeing:

#1056

C:/deno/js/file_test.ts:5:20 - error TS2552: Cannot find name 'File'. Did you mean 'file'?
5   const file = new File(arg1, "name");
                     ~~~~

#1088

C:/deno/js/chmod_test.ts:18:8 - error TS2339: Property 'chmodSync' does not exist on type 'typeof import("deno")'.
18   deno.chmodSync(filename, 0o777);
          ~~~~~~~~~

[piscisaureus]

Sorry but this change has nothing to do with the issues it is intended to solve.
The hasher is only active when (s)ccache is in use - it isn't on appveyor.

[ry]

ok - my bad