Add the OPAQUE pragma

A new pragma, `OPAQUE`, that ensures that every call of a named
function annotated with an `OPAQUE` pragma remains a call of that
named function, not some name-mangled variant.

Implements GHC proposal 0415:
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0415-opaque-pragma.rst

This commit also updates the haddock submodule to handle the newly
introduced lexer tokens corresponding to the OPAQUE pragma.

1 files changed, 0 insertions, 0 deletions

diff --git a/utils/haddock b/utils/haddock
-Subproject d2779a3e659d4e9f7044c346a566e5fe4edbdb9
+Subproject 559e41505e81d93939e9afa6aa9793b0a428924