esp8266/mpconfigport.h: Make socket a weak link

This way it can be overridden by a socket module in Python, as in other
ports.

esp8266/mpconfigport.h

@@ -162,7 +162,6 @@ extern const struct _mp_obj_module_t mp_module_onewire;
 
 #define MICROPY_PORT_BUILTIN_MODULES \
     { MP_OBJ_NEW_QSTR(MP_QSTR_esp), (mp_obj_t)&esp_module }, \
-    { MP_OBJ_NEW_QSTR(MP_QSTR_socket), (mp_obj_t)&mp_module_lwip }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_usocket), (mp_obj_t)&mp_module_lwip }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_network), (mp_obj_t)&network_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_utime), (mp_obj_t)&utime_module }, \
@@ -176,6 +175,7 @@ extern const struct _mp_obj_module_t mp_module_onewire;
     { MP_OBJ_NEW_QSTR(MP_QSTR_json), (mp_obj_t)&mp_module_ujson }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_errno), (mp_obj_t)&mp_module_uerrno }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_select), (mp_obj_t)&mp_module_uselect }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_socket), (mp_obj_t)&mp_module_lwip }, \
 
 #define MP_STATE_PORT MP_STATE_VM