Update WebP from 0.4.0 to 0.4.1
Make WebP with 4 job slots - ~2.4 times faster
Make OpenJPEG with 4 job slots - ~2.2 times faster
Make OpenJPEG with 4 job slots - ~2.2 times faster (take 2)
Merge pull request #864 from hugovk/make-j

Update WebP and build it and OpenJPEG with 4 job slots