10.6.8 and ffmpeg

[Ryan Schmidt]

> On Oct 29, 2016, at 12:05 AM, Ken Cunningham <ken.cunningham.webuse at gmail.com> wrote:
> 
> libsdl2 will build without trouble on 10.6.8 if you find a copy of the 10.7 SDK and put it like so in /Developer/SDKs/MacOSX10.7.sdk

That is not a procedure we have ever recommended users do before. I know that using the 10.12 SDK on 10.11 will work. If using the 10.7 SDK on 10.6 will work, and we want to help users do that, maybe we should have a documented way for the user to do that. And maybe we should install the 10.7 SDK on the 10.6 buildbot machines so that these ports can be built automatically.