Summary:
D2716 introduced colors into the output of GHC.
These color ourputs are done using escape characters output
to the terminal.

These however are wreaking havoc on the testsuite output as now
no stderr with a warning or error will match anymore.

Instead of accepting the new codes as expected values instead I
turn them off. So the testsuite is consistent on platforms/terminals we
don't support colors on.

Test Plan:
any test that outputs colors. e.g.

make test TEST=T9576

Reviewers: austin, Rufflewind, bgamari

Subscribers: thomie, #ghc_windows_task_force

Differential Revision: https://phabricator.haskell.org/D2787

GHC Trac Issues: #8809