[commit: ghc] master: Update docker images to use GHC 8.4.2 and cabal-install-2.2 (56e8c6f)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/56e8c6fc9d65fec11485bd02d437a753bc1a4ebe/ghc

>---------------------------------------------------------------

commit 56e8c6fc9d65fec11485bd02d437a753bc1a4ebe
Author: mrkkrp <markkarpov92 at gmail.com>
Date:   Thu Apr 26 15:12:15 2018 +0700

    Update docker images to use GHC 8.4.2 and cabal-install-2.2
    
    The ‘haskell’ images are not being updated and there is no image with GHC
    8.4.2, so we probably should not use them anymore. I adapted Dockerfiles
    used by those images so the end result is almost the same except we get
    newer GHC and cabal-install.


>---------------------------------------------------------------

56e8c6fc9d65fec11485bd02d437a753bc1a4ebe
 .circleci/config.yml                            | 16 ++++++++--------
 .circleci/images/i386-linux/Dockerfile          | 19 +++++++------------
 .circleci/images/x86_64-linux-fedora/Dockerfile | 10 +++++-----
 .circleci/images/x86_64-linux/Dockerfile        | 23 ++++++++++++++++++-----
 4 files changed, 38 insertions(+), 30 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 56e8c6fc9d65fec11485bd02d437a753bc1a4ebe