Michal Terepeta authored Oct 04, 2018 and Ben Gamari committed Oct 07, 2018

This is the first step of implementing:
https://github.com/ghc-proposals/ghc-proposals/pull/74



The main highlights/changes:

- `primops.txt.pp` gets two new sections for two new primitive types
  for signed and unsigned 8-bit integers (`Int8#` and `Word8`
  respectively) along with basic arithmetic and comparison
  operations. `PrimRep`/`RuntimeRep` get two new constructors for
  them. All of the primops translate into the existing `MachOP`s.

- For `CmmCall`s the codegen will now zero-extend the values at call
  site (so that they can be moved to the right register) and then
  truncate them back their original width.

- x86 native codegen needed some updates, since it wasn't able to deal
  with the new widths, but all the changes are quite localized. LLVM
  backend seems to just work.

Bumps binary submodule.

Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

Test Plan: ./validate with new tests

Reviewers: hvr, goldfire, bgamari, simonmar

Subscribers: Abhiroop, dfeuer, rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4475