Release 8.6.1

Revert "rts: Ensure that the_gc_thread is aligned"

This reverts commit 87a79e3.

Fix processHeapClosureForDead CONSTR_NOCAF case

CONSTR_NOCAF was introduced with 55d535d as a replacement for
CONSTR_STATIC and CONSTR_NOCAF_STATIC, however, as explained in Note
[static constructors], we copy CONSTR_NOCAFs (which can also be seen in
evacuate) during GC, and they can become dead, like other CONSTR_X_Ys.
processHeapClosureForDead is updated to reflect this.

Test Plan: Validates on x86_64. Existing failures on i386.

Reviewers: simonmar, bgamari, erikd

Reviewed By: simonmar, bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #7836, #15063, #15087, #15165

Differential Revision: https://phabricator.haskell.org/D4928

(cherry picked from commit 2625f13)

Fix error recovery for pattern synonyms

As Trac #15289 showed, we were carrying on after a type error
in a pattern synonym, and then crashing.  This patch improves
error handling for pattern synonyms.

I also moved a bit of code from TcBinds into TcPatSyn, which
helpfully narrows the API.

(cherry picked from commit 2896082)

Release 8.4.3

Release 8.4.2

Bump haddock submodule again

Release 8.4.1

Start of GHC 8.5 development branch

(This annotated tag helps tools such as `git describe`)

Bump unix submodule back to 2.7