lwip: patch for resetting write offset

Otherwise, the assertion "already writing or closing" may fail.

repos/libports/ports/lwip.hash

@@ -1 +1 @@
-3608c569747383625a1bca182683c3668fa630b5
+136ee70f33ffced072262d589c24ab3252d15eff

repos/libports/ports/lwip.port

@@ -14,7 +14,8 @@ PATCHES := $(addprefix src/lib/lwip/,window_scaling.patch \
                                      errno.patch \
                                      libc_select_notify.patch \
                                      sockets_c_errno.patch \
-                                     sol_socket_definition.patch)
+                                     sol_socket_definition.patch \
+                                     api_msg.patch)
 
 PATCH_OPT := -p1 -d src/lib/lwip
 

repos/libports/src/lib/lwip/api_msg.patch

@@ -0,0 +1,13 @@
+The write offset was not always reset after a write finished resulting in the
+failed assertion "already writing or closing".
+
+--- a/src/api/api_msg.c
++++ b/src/api/api_msg.c
+@@ -1340,6 +1340,7 @@ err_mem:
+        and back to application task */
+     conn->current_msg->err = err;
+     conn->current_msg = NULL;
++    conn->write_offset = 0;
+     conn->state = NETCONN_NONE;
+ #if LWIP_TCPIP_CORE_LOCKING
+     if ((conn->flags & NETCONN_FLAG_WRITE_DELAYED) != 0)