[Mesa-stable] Mesa 19.0 only nominations

[Emil Velikov]

Hi Jason,

spirv: Pull offset/stride from the pointer for OpArrayLength
anv: Refactor descriptor pushing a bit
anv: Take references to push descriptor set layouts
nir: Add a pass for lowering IO back to vector when possible
intel/nir: Vectorize all IO

The above commits are explicit 19.0 nominations or otherwise require
additional patched, which are not present in the 18.3 branch.

As such I'm inclined to keep them out of the 18.3 series, esp. with
19.0.0 just released.
Let me know if they are critical fixes and if so, can we have some
backports [1].

Thanks
Emil
[1] https://www.mesa3d.org/submittingpatches.html#backports