Added handling of av_len = 0 etc in C_SocksSetup

rtmp/rtmp.go

@@ -591,6 +591,10 @@ func C_SocksSetup(r *C.RTMP, sockshost *C.AVal) {
 			}
 			r.Link.socksport = C.ushort(value)
 		}
+	} else {
+		r.Link.sockshost.av_val = nil
+		r.Link.sockshost.av_len = 0
+		r.Link.socksport = 0
 	}
 }