Summary:
D2461 seemed to (inadvertently, I think) add the
`-flocal-ghci-history` flag to the list of `defaultFlags` that are enabled
automatically. As a result, every invocation of `ghci` caused a local GHCi
history to be saved to the current directory, which probably shouldn't be the
default.

Test Plan:
Run `ghci`, observe the lack of a `.ghci_history` file in your
working directory

Reviewers: austin, thomie, bgamari

Reviewed By: bgamari

Subscribers: ak3n

Differential Revision: https://phabricator.haskell.org/D2520

GHC Trac Issues: #9089