Add libprocessgroup dependency and fix sched_policy include

Because android_runtime is using set_sched_policy which is moved
into libprocessgroup an additional dependency is added and header
file change is made.

Exempt-From-Owner-Approval: janitorial

Bug: 111307099
Test: builds, boots
Change-Id: I98a7a6f9a9d6be8595b3604fb73dafc05412c482
Signed-off-by: Suren Baghdasaryan <surenb@google.com>