Blender Git Loki

Cycles: Fix correlation issues in certain cases

There were two cases where correlation issues were obvious:

- File from T38710 was giving issues in 2.78a again
- File from T50116 was having totally different shadow between
sample 1 and sample 32.

Use some more simplified version of CMJ hash which seems to give
nice randomized value which solves the correlation.

This commit will break all unit test files, but it's a bug fix
so perhaps OK to commit this.

This also fixes T41143: Sobol gives nonuniform noise

Proper science paper about hash function is coming.

Reviewers: brecht

Reviewed By: brecht

Subscribers: lukasstockner97

Differential Revision: https://developer.blender.org/D2385