Tamar Christina authored Oct 03, 2017 and Ben Gamari committed Oct 03, 2017

It's often hard to debug things like segfaults on Windows,
mostly because gdb isn't always of use and users don't know
how to effectively use it.

This patch provides a way to create a crash drump by passing

`+RTS --generate-crash-dumps` as an option. If any unhandled
exception is triggered a dump is made that contains enough
information to be able to diagnose things successfully.

Currently the created dumps are a bit big because I include
all registers, code and threads information.

This looks like

```
$ testsuite/tests/rts/derefnull.run/derefnull.exe +RTS
--generate-crash-dumps

Access violation in generated code when reading 0000000000000000
Crash dump created. Dump written to:
        E:\msys64\tmp\ghc-20170901-220250-11216-16628.dmp
```

Test Plan: ./validate

Reviewers: austin, hvr, bgamari, erikd, simonmar

Reviewed By: bgamari, simonmar

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3912