py/mpstate.h: Add repl_line state for MICROPY_REPL_EVENT_DRIVEN.

py/mpstate.h

@@ -166,6 +166,10 @@ typedef struct _mp_state_vm_t {
 
     // root pointers for extmod
 
+    #if MICROPY_REPL_EVENT_DRIVEN
+    vstr_t *repl_line;
+    #endif
+
     #if MICROPY_PY_OS_DUPTERM
     mp_obj_t dupterm_objs[MICROPY_PY_OS_DUPTERM];
     mp_obj_t dupterm_arr_obj;