Sorry, I mixed things up. On Debian Testing libsdl2-dev (2.0.8+dfsg1-1) supports multiarch and it's libxkbcommon-dev that ruins it for everyone (see bug 893855).
But I'm also working on a Debian 9.4 VM and there libsdl2-dev 2.0.5+dfsg1-2 does not support multiarch. I got confused and thought both issues had the same source. So while I'd still really like libsdl2-dev to support multiarch in Debian Stable (because that's what people are told to use after all and it would be consistent with point 4 of the Social Contract), I can understand if this bug gets closed.  We will be guided by the needs of our users and the free software community. We will place their interests first in our priorities. We will support the needs of our users for operation in many different kinds of computing environments. https://www.debian.org/social_contract -- Francois Gouget <fgou...@free.fr> http://fgouget.free.fr/ Before you criticize someone, walk a mile in his shoes. That way, if he gets angry, he'll be a mile away - and barefoot.