Introduce an explicit processRaftMu.
Introduce an explicit processRaftMu.

This replaces the implicit locking of "running on the processRaft
goroutine".

paperstreet/cockroach,maxlang/cockroach,sunya123/cockroach,paperstreet/cockroach,petermattis/cockroach,veteranlu/cockroach,glycerine/cockroach,vaibhavarora/cockroach,petermattis/cockroach,arjun4084346/cockroach,nieyy/cockroach,sunya123/cockroach,paperstreet/cockroach,nieyy/cockroach,nieyy/cockroach,glycerine/cockroach,vaibhavarora/cockroach,arjun4084346/cockroach,vaibhavarora/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,maxlang/cockroach,arjun4084346/cockroach,vaibhavarora/cockroach,petermattis/cockroach,vaibhavarora/cockroach,sunya123/cockroach,sunya123/cockroach,arjun4084346/cockroach,bg451/cockroach,nieyy/cockroach,bg451/cockroach,vivekmenezes/cockroach,cuongdo/cockroach,nieyy/cockroach,bg451/cockroach,cuongdo/cockroach,cockroachdb/cockroach,cuongdo/cockroach,glycerine/cockroach,maxlang/cockroach,cockroachdb/cockroach,cuongdo/cockroach,veteranlu/cockroach,cuongdo/cockroach,paperstreet/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,sunya123/cockroach,vivekmenezes/cockroach,glycerine/cockroach,vivekmenezes/cockroach,glycerine/cockroach,veteranlu/cockroach,arjun4084346/cockroach,arjun4084346/cockroach,nieyy/cockroach,cockroachdb/cockroach,cuongdo/cockroach,bg451/cockroach,il9ue/cockroach,veteranlu/cockroach,cockroachdb/cockroach,maxlang/cockroach,petermattis/cockroach,il9ue/cockroach,cuongdo/cockroach,vaibhavarora/cockroach,paperstreet/cockroach,cuongdo/cockroach,il9ue/cockroach,petermattis/cockroach,cockroachdb/cockroach,sunya123/cockroach,veteranlu/cockroach,nieyy/cockroach,glycerine/cockroach,maxlang/cockroach,sunya123/cockroach,vivekmenezes/cockroach,petermattis/cockroach,paperstreet/cockroach,vivekmenezes/cockroach,maxlang/cockroach,il9ue/cockroach,vivekmenezes/cockroach,il9ue/cockroach,il9ue/cockroach,veteranlu/cockroach,maxlang/cockroach,il9ue/cockroach,veteranlu/cockroach,il9ue/cockroach,nieyy/cockroach,veteranlu/cockroach,sunya123/cockroach,vivekmenezes/cockroach,bg451/cockroach,maxlang/cockroach,glycerine/cockroach,bg451/cockroach,vivekmenezes/cockroach,glycerine/cockroach,petermattis/cockroach,bg451/cockroach,paperstreet/cockroach,arjun4084346/cockroach,petermattis/cockroach,arjun4084346/cockroach,paperstreet/cockroach