Fix #8958.

We now do role inference on stupid datatype contexts, allowing a
lightweight role annotation syntax.

(cherry picked from commit d468cd376ffc02cf9f4755275a316be914c482be)
windows: Fix #8870

This bumps the amount of default reserved and committed stack for GHC
executables to 8mb, to work around #8870. A proper fix should happen in
7.8.2

See note [Windows stack usage] in SysTools for the details.

Signed-off-by: Austin Seipp <austin@well-typed.com>
(cherry picked from commit f0af58df4b5d5ace750e7d7a91ad471284c1b429)
Make sure that polykinded Typeable is defaultable (Trac #8931)

(cherry picked from commit 791f4fa24dd6929ab2e55c9f8b870d8078337427)
Test Trac #8931

(cherry picked from commit 8bf8ce1e7cb1b97a1f18ec6f5552e339808ffba9)
Fix copy/paste error (#8937)

(cherry picked from commit 59b9b067b030d551f9b42423b50770c661c9d86c)
Fix desguaring of bang patterns (Trac #8952)

A palpable bug, although one that will rarely bite

(cherry picked from commit 3671d0027329804a31a628a5bee355e0640a2045)
Revert "Revert ad15c2, which causes Windows seg-faults (Trac #8834)"

This reverts commit a79613a75c7da0d3d225850382f0f578a07113b5.

(cherry picked from commit c6c86789c95462216a3167d7b98b202a5bf4c0b2)
Require PatternSynonyms language flag when encountering a use of pattern synonym
(#8961)

(cherry picked from commit 8f831ec578d22419788542290e164c50524d90f6)
T8958: fix stderr

Signed-off-by: Austin Seipp <austin@well-typed.com>