multiview: partial fix for FSA breakage
(the error was introduced after the windows fix)

the bug that I still get comes with a few error messages such as:
IMB_exr_set_channel error RenderLayer.Depth.ed.left.A

This mangled names suggest me either we have a threading problem, or
something is going wrong with string copying

Rendering with single thread my "solve" this (or better with one huge
tile at least)
Merge branch 'multiview' of github.com:dfelinto/blender into multiview