Do not copy stack after stack overflow, refix #8435

Summary:
This was reverted in d70b19bf
and is a part of the reason for #10445.

Test Plan: validate

Reviewers: ezyang, simonmar, austin

Reviewed By: simonmar, austin

Subscribers: bgamari, thomie

Differential Revision: https://phabricator.haskell.org/D938

GHC Trac Issues: #8435

(cherry picked from commit 892c3e98)