Suggest how to fix .ghci when it is group writeable (#8248)
Suggest how to fix .ghci when it is group writeable (#8248)

```
chmod 664 $PATH_TO_GHCI_CONF/.ghci
```

Run ghci. You will now get a warning + a suggestion:

```
  *** WARNING: $PATH_TO_GHCI_CONF/.ghci is writable by someone else, IGNORING!
  Suggested fix: execute 'chmod 644 $PATH_TO_GHCI_CONF/.ghci'
```

Execute fix and the warning should disappear.

Reviewed By: mboes, thomie

Differential Revision: https://phabricator.haskell.org/D805

(cherry picked from commit b972de0365f94e1be9d78537152eee969dc5f4cb)

forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc,forked-upstream-packages-for-ghcjs/ghc