configure: Add info about build dir.
configure: Add info about build dir.

superboy0712/realtime,superboy0712/realtime,superboy0712/realtime,superboy0712/realtime,vlstill/ttk4145,superboy0712/realtime,vlstill/ttk4145,vlstill/ttk4145,vlstill/ttk4145,superboy0712/realtime,vlstill/ttk4145,vlstill/ttk4145