Blender Git Loki

Color Management: fix crash when strip failed to render

In this case sequencer would allocate empty image buffer which used to not to
have assigned color spaces but it was marked as non-linear float.

Assuming black would always be black in sequencer's color space no additional
transformation for display is needed.

Solved by removing NOLINEAR_FLOAT flag from image buffers and using check
image buffer's float_colorspace for NULL when needed to check whether float
buffer is linear or not.