Add per UID interface support to resolv cache

Add methods to attach/detach UID ranges to a specific dns cache/interface.

This mirrors the already existing code for attaching specific processes to
specific interfaces but will be used to push all processes from a given
user to a specific cache/interface.

Change-Id: Ic24391e92d3ca46fcb46cc4fc53e13984dec40b3
2 files changed