More migration of syncrepl from frontend to syncprov overlay

servers/slapd/back-bdb/init.c

servers/slapd/back-monitor/init.c

servers/slapd/backglue.c

servers/slapd/connection.c

servers/slapd/controls.c

servers/slapd/ldapsync.c

servers/slapd/operation.c

servers/slapd/overlays/pcache.c

servers/slapd/overlays/syncprov.c

servers/slapd/proto-slap.h

servers/slapd/search.c

servers/slapd/sessionlog.c

servers/slapd/slap.h

servers/slapd/slapacl.c

servers/slapd/slapauth.c

servers/slapd/syncrepl.c