Alec Theriault authored Apr 18, 2019 and Marge Bot committed Apr 19, 2019

Rather than massaging the output of the parser to re-arrange docs and
bangs, it is simpler to patch the two places in which the strictness
info is needed (to accept that the `HsBangTy` may be inside an
`HsDocTy`).

Fixes #16585.