That commit illegaly polled SDL events from a different thread which for
an unknown reason did not error on Windows and GNU/linux.
Refs #4822 / D1304, similarly 8fec942e8a.
Differential Revision: https://code.wildfiregames.com/D1484
Previous iteration tested on OSX and some comments with regards to
letter case by Vladislav (refs 27da92e55f, 4c73614955).
This was SVN commit r21818.