py/repl: Skip private variables when printing tab completion options.

Any '_' variables/functions in frozen modules are currently printed.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: pi-anl

py/repl.c

@@ -218,7 +218,7 @@ static void print_completions(const mp_print_t *print,
     for (qstr q = q_first; q <= q_last; ++q) {
         size_t d_len;
         const char *d_str = (const char *)qstr_data(q, &d_len);
-        if (s_len <= d_len && strncmp(s_start, d_str, s_len) == 0) {
+        if (s_len <= d_len && strncmp(s_start, d_str, s_len) == 0 && d_str[0] != '_') {
             if (test_qstr(obj, q)) {
                 int gap = (line_len + WORD_SLOT_LEN - 1) / WORD_SLOT_LEN * WORD_SLOT_LEN - line_len;
                 if (gap < 2) {