Add libprocessgroup dependency and fix sched_policy include

surfaceflinger, installd and libvrflinger are using set_sched_policy
which is moved into libprocessgroup. Add libprocessgroup dependency
and include required headers.

Exempt-From-Owner-Approval: janitorial

Bug: 111307099
Test: builds, boots

Merged-In: Iccb7c54a85ca148d44ce687fe05e89ad4369e104
Change-Id: Iccb7c54a85ca148d44ce687fe05e89ad4369e104
Signed-off-by: Suren Baghdasaryan <surenb@google.com>