Merge commit 'f56fa95c'

* commit 'f56fa95c':
  swscale: Do not shift negative values directly

14:30:21] <jamrial> michaelni: do you prefer how f56fa95c (libav) handles left shift of negative value, or how we're currently doing it?
[14:30:31] <jamrial> ours is cleaner looking, IMO
[14:30:57] <@ubitux> i agree
[14:31:13] <@ubitux> if we didn't forget any, i think this commit is better noop'ed
[14:31:57] <jamrial> ubitux: we even have a bunch of other cases this commit doesn't handle that i'd have to manually change, so yeah, i'm leaning towards nooping it
[14:34:04] <michaelni> jamrial, +1, ours as its cleaner

This commit is a noop.
Merged-by: James Almer <jamrial@gmail.com>