[unity] Port of commit 25bd863: Reverse IK bend positive logic.[..]Requires 4.3.39-beta+.

spine-csharp/src/SkeletonBinary.cs

@@ -255,7 +255,7 @@ namespace Spine {
 						data.skinRequired = (flags & 1) != 0;
 						data.uniform = (flags & 2) != 0;
 						IkConstraintPose setup = data.setup;
-						setup.bendDirection = (flags & 4) != 0 ? 1 : -1;
+						setup.bendDirection = (flags & 4) != 0 ? -1 : 1;
 						setup.compress = (flags & 8) != 0;
 						setup.stretch = (flags & 16) != 0;
 						if ((flags & 32) != 0) setup.mix = (flags & 64) != 0 ? input.ReadFloat() : 1;