Warning fixes

The one I'm a little unsure about is f56802453eac08cf7e3be875cb8853fe414a7b33, but I think it's correct.

This makes things much closer to warning free.  There's an incorrect (afaict) warning in `SoftwareTransformAndDraw()`, 2 in snappy, 1 in native, and a multiline comment warning.  There's more with clang but meh.

There's also the imported thing with ffmpeg on Windows, but I dunno why.

-[Unknown]