ghc-cmark-gfm-0.1.6-bp151.2.2

- Update cmark-gfm to version 0.1.6.
  cmark-gfm 0.1.6 (17 Oct 2018)
  * Update to cmark-gfm 0.28.3.gfm.18.
  * `optUnsafe` is now exposed, instead of `optSafe`.

- Update cmark-gfm to version 0.1.5.
  cmark-gfm 0.1.5 (21 Aug 2018)
  * Update to cmark-gfm 0.28.3.gfm.15.
  * Fix build with system cmark-gfm (Felix Yan, #9).

- Update cmark-gfm to version 0.1.4.
  cmark-gfm 0.1.4 (2 Jul 2018)
  * Extensions work correctly on big-endian systems (Ilias Tsitsimpis).

- Add cmark-gfm at version 0.1.3.