[Docker build] removed max-backjumps

With max-backjumps=-1 cabal can not resolve dependencies building
ghcjs and ghcjs-prim, without it it succeeds.

I don't understand cabal well enough to understand what this means,
though I am glad it is building.
Merge branch 'master' of https://github.com/ghcjs/ghcjs
[Docker build] corrected typo that let build fail

--max-backjumps=-1 had the one missing, that way cabal could not resolve
dependencies.
Merge pull request #277 from atddio/master

[Docker][Fix] docker image now builds correctly