ghc: 7.8.3

Starts the process of closing [31609](https://github.com/Homebrew/homebrew/issues/31609). The patches previous in :DATA have been merged with this release and consequently are no longer required. There is also currently no dev build available, so that has been scrapped as well.
I removed it, and put another unindented ``` end ``` at the bottom of the formula, which has resulted in it passing locally again. Slightly concerned why the last build would have passed a local audit only to fail the Bot's audit, but hopefully the new commit will have better luck. I feel like I'm missing something blindingly obvious, but I can't see what it would be.