windows: correct misspelling in comment
windows: correct misspelling in comment

The comment for ConsoleScreenBufferInfo uses the word 'retreive' that
is a misspelling of 'retrieve'.

Change-Id: Idd9fb0c5082b6a2b10badbbb162e312710bfe68b
GitHub-Last-Rev: 08d62a57df113291ea0abd7198bae7d15fa6f075
GitHub-Pull-Request: golang/sys#18
Reviewed-on: https://go-review.googlesource.com/134221
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

golang/sys,golang/sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys,golang/sys,multiplay/golang-sys