builtin: Reimplement __repl_print__() in terms of print().

Before, __repl_print__() used libc printf(), while print() used uPy streams
and own printf() implementation. This led to subtle, but confusing
differences in output when just doing "foo" vs "print(foo)" on interactive
prompt.

py/builtin.c

@@ -89,15 +89,6 @@ STATIC mp_obj_t mp_builtin___build_class__(mp_uint_t n_args, const mp_obj_t *arg
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR(mp_builtin___build_class___obj, 2, mp_builtin___build_class__);
 
-STATIC mp_obj_t mp_builtin___repl_print__(mp_obj_t o) {
-    if (o != mp_const_none) {
-        mp_obj_print(o, PRINT_REPR);
-        printf("\n");
-    }
-    return mp_const_none;
-}
-MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin___repl_print___obj, mp_builtin___repl_print__);
-
 STATIC mp_obj_t mp_builtin_abs(mp_obj_t o_in) {
     if (MP_OBJ_IS_SMALL_INT(o_in)) {
         mp_int_t val = MP_OBJ_SMALL_INT_VALUE(o_in);
@@ -452,6 +443,14 @@ STATIC mp_obj_t mp_builtin_print(mp_uint_t n_args, const mp_obj_t *args, mp_map_
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_print_obj, 0, mp_builtin_print);
 
+STATIC mp_obj_t mp_builtin___repl_print__(mp_obj_t o) {
+    if (o != mp_const_none) {
+        mp_builtin_print(1, &o, (mp_map_t*)&mp_const_empty_map);
+    }
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin___repl_print___obj, mp_builtin___repl_print__);
+
 STATIC mp_obj_t mp_builtin_repr(mp_obj_t o_in) {
     vstr_t *vstr = vstr_new();
     mp_obj_print_helper((void (*)(void *env, const char *fmt, ...))vstr_printf, vstr, o_in, PRINT_REPR);