BUG/MEDIUM: muxes: Use the right argument when calling the destroy method.

When calling the mux "destroy" method, the argument should be the mux
context, not the connection. In a few instances in the mux code, the
connection was used (mainly when the session wouldn't handle the idle
connection, and the server pool was fool), and that could lead to random
segfaults.

This should be backported to 2.1, 2.0, and 1.9

src/mux_fcgi.c

@@ -3468,7 +3468,7 @@ static void fcgi_detach(struct conn_stream *cs)
 				if (eb_is_empty(&fconn->streams_by_id)) {
 					if (!srv_add_to_idle_list(objt_server(fconn->conn->target), fconn->conn)) {
 						/* The server doesn't want it, let's kill the connection right away */
-						fconn->conn->mux->destroy(fconn->conn);
+						fconn->conn->mux->destroy(fconn);
 						TRACE_DEVEL("outgoing connection killed", FCGI_EV_STRM_END|FCGI_EV_FCONN_ERR);
 					}
 					TRACE_DEVEL("reusable idle connection", FCGI_EV_STRM_END, fconn->conn);

src/mux_h1.c

@@ -2396,7 +2396,7 @@ static void h1_detach(struct conn_stream *cs)
 				h1c->conn->owner = NULL;
 				if (!srv_add_to_idle_list(objt_server(h1c->conn->target), h1c->conn)) {
 					/* The server doesn't want it, let's kill the connection right away */
-					h1c->conn->mux->destroy(h1c->conn);
+					h1c->conn->mux->destroy(h1c);
 					TRACE_DEVEL("outgoing connection killed", H1_EV_STRM_END|H1_EV_H1C_END);
 					goto end;
 				}

src/mux_h2.c

@@ -3887,7 +3887,7 @@ static void h2_detach(struct conn_stream *cs)
 					if (eb_is_empty(&h2c->streams_by_id)) {
 						if (!srv_add_to_idle_list(objt_server(h2c->conn->target), h2c->conn))
 							/* The server doesn't want it, let's kill the connection right away */
-							h2c->conn->mux->destroy(h2c->conn);
+							h2c->conn->mux->destroy(h2c);
 						TRACE_DEVEL("leaving on error after killing outgoing connection", H2_EV_STRM_END|H2_EV_H2C_ERR);
 						return;
 					}