wereHamster authored May 08, 2016 and Ben Gamari committed May 10, 2016

We can't define Stg{Int,Word} in terms of {,u}intptr_t because STG
depends on them being the exact same size as void*, and {,u}intptr_t
does not make that guarantee. Furthermore, we also need to define
StgHalf{Int,Word}, so the preprocessor if needs to stay. But we can at
least keep it in a single place instead of repeating it in various
files.

Also define STG_{INT,WORD}{8,16,32,64}_{MIN,MAX} and use it in HsFFI.h,
further reducing the need for CPP in other files.

Reviewers: austin, bgamari, simonmar, hvr, erikd

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2182