REORG: thread/sched: move the last dynamic thread_info to thread_ctx

The last 3 fields were 3 list heads that are per-thread, and which are:
  - the pool's LRU head
  - the buffer_wq
  - the streams list head

Moving them into thread_ctx completes the removal of dynamic elements
from the struct thread_info. Now all these dynamic elements are packed
together at a single place for a thread.
14 files changed