testsuite: Separate out Windows results for T5205
testsuite: Separate out Windows results for T5205

This test seems to have much different allocation behavior on Windows
and Linux.  Previously we had widened the acceptance window to 7% to
accomodate this, but even this isn't enough any more. Instead of further
widening the window let's just give an expected number for each
platform. Really, this is precisely the issue with our performance
testing model which I've been complaining about in #12758.

Fixes test for #5205 on 64-bit Windows.

Test Plan: Validate on Windows

Reviewers: austin

Subscribers: thomie, Phyx

Differential Revision: https://phabricator.haskell.org/D2848

GHC Trac Issues: #5205

sdiehl/ghc,shlevy/ghc,ezyang/ghc,ezyang/ghc,olsner/ghc,shlevy/ghc,ezyang/ghc,shlevy/ghc,ezyang/ghc,olsner/ghc,sdiehl/ghc,shlevy/ghc,ezyang/ghc,ezyang/ghc,ezyang/ghc,olsner/ghc,shlevy/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,shlevy/ghc,olsner/ghc,olsner/ghc,shlevy/ghc,sdiehl/ghc,olsner/ghc,sdiehl/ghc,olsner/ghc