Alec Theriault authored Jan 10, 2019 and Ben Gamari committed Jan 16, 2019

Fixes #16105

  * Require Haddock's resource as runtime dependencies of the Haddock
    builder. This means we no longer have to `need` particular resources
    in every other documentation rule.

  * Do a _tracked_ copy of both the 'html' and 'latex' folder resource
    folders.

  * Move resources into `stage1/lib` (NB: the `haddock` binary goes in
    `stage1/bin`). Besides now actually matching the Haddock script
    wrapper generated by BinaryDist, this also prepares for Haddock
    in relocatable build folder detecting its own resources.