CacheLocality: reserve less space on mobile
CacheLocality: reserve less space on mobile

Summary: Mobile phones have more like 16 CPUs and less like 128 CPUs.

Reviewed By: yfeldblum

Differential Revision: D16151292

fbshipit-source-id: 87caed64d9a874f71e85ee2842194405e43568a3

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly