I opened upstream bug. Please consider adding this patch to stable.
what patch?
http://bugzilla.libsdl.org/show_bug.cgi?id=1486 http://bugzilla.libsdl.org/attachment.cgi?id=850
Created attachment 314427 [details, diff] libsdl-1.2.15-joystick.patch Backpoted from upstream. Verified.
libsdl-1.2.15-r2.ebuild added with the upstream patch.