Create arch specific cache dirs during zygote startup.

The runtime expects them to exist before it's launched.
The boot image / art files are created during the first
zygote launch.

(cherry picked from commit da738713e4e2120a324e8ab6fd11aa0e54a3c66e)

Change-Id: I7472aa25c16a1cf95791af2bdf80ed0d73123872