Simple corrupted compiled file detection

Question

We should include a line at the end of the file that we check for to determine that the file was not corrupted due to either an incomplete write or a clobbered write. It should be be the SHA of the ClojureScript source it was generated from.

Answer 1

Reference: https://clojure.atlassian.net/browse/CLJS-1125 (reported by dnolen)