Kill obsolete pre GHC 7.6 bootstrapping support

This left-over is definitely not needed anymore
and was probably missed in 527bcc41630918977c7
Make GHC `time-1.5`-ready

This also updates a few submodules to have their upper-bounds on
`time` relaxed to allow `time-1.5`. The only package that can't be
upgraded yet is `Cabal` due to API changes breaking `ghc-cabal`. This
needs to be addressed in a future commit.