Summary:
D2752 added some tests which escapes string literals. This means newlines are converted
before they get normalized by the IO functions. So on Windows \r\n would be in the output
while \n was expected.

Test Plan: make test -C testsuite/tests/printer

Reviewers: austin, bgamari, alanz

Reviewed By: alanz

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2873

GHC Trac Issues: #3384