Fix for render results acquire/release in viewport render, should only release
after drawing to be thread safe.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56111 954f8c5b-7b00-dc11-b283-0030488c597c
Fix #35004: fireflies with .tif image in cycles, try to avoid extreme values when
openimageio can't detect premul/straight alpha correct.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56112 954f8c5b-7b00-dc11-b283-0030488c597c
Cycles: initialize LCG for sss and hair sampling without using the sobol sampler,
slightly faster but also fixes the u/v sampling dimensions not longer being at even
values which is needed for best results.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56113 954f8c5b-7b00-dc11-b283-0030488c597c