gnu: haskell-mode: Update to 16.1.

* gnu/packages/emacs.scm (haskell-mode): Update to 16.1.
  [inputs]: Add 'emacs-el-search' and 'emacs-stream'.
  [propagated-inputs]: Add 'emacs-dash'.
  [arguments]: Add modules. Adapt 'pre-build' and 'install' phases.