Sequencer, scene render (work in progress)

Rendering crashes after a few attempts (or a few frames when rendering a
sequencer). It seems memory related.

The overall problem is that the re->result is not consistent across the
entire render session it seems. Still investigating.
Sequencer render of scene strips working fine

Basically the issue was that rr was being freed and re-allocated inside
the BKE_sequencer_give_ibuf() function - more specifically after
RE_InitState() calls render_result_free().

Thanks to Jens Verwiebe for the help in cross-debug this.