Fix that `print` command raises `FrozenError` in `mrdb`; ref
#### Before this patch:
```
$ echo 'p true' | bin/mrdb /dev/null
(/dev/null:1) mruby application exited.
FrozenError: can't modify frozen String
(-:0)
```
#### After this patch:
```
$ echo 'p true' | bin/mrdb /dev/null
(/dev/null:1) $1 = true
(/dev/null:1)
```
MODIFY
mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c
mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c
@@ -74,7 +74,7 @@ mrb_debug_eval(mrb_state *mrb, mrb_debug_context *dbg, const char *expr, size_t
*exc = mrb_obj_is_kind_of(mrb, v, mrb->eException_class);
}
- s = mrb_funcall(mrb, v, "inspect", 0);
+ s = mrb_inspect(mrb, v);
/* enable code_fetch_hook */
mrb->code_fetch_hook = tmp;

MODIFY
mrbgems/mruby-bin-debugger/tools/mrdb/cmdprint.c
mrbgems/mruby-bin-debugger/tools/mrdb/cmdprint.c
@@ -18,7 +18,6 @@ dbgcmd_print(mrb_state *mrb, mrdb_state *mrdb)
{
mrb_value expr;
mrb_value result;
- mrb_value s;
uint8_t wcnt;
int ai;
@@ -39,8 +38,9 @@ dbgcmd_print(mrb_state *mrb, mrdb_state *mrdb)
result = mrb_debug_eval(mrb, mrdb->dbg, RSTRING_PTR(expr), RSTRING_LEN(expr), NULL, 0);
/* $print_no = result */
- s = mrb_str_cat_lit(mrb, result, "\0");
- printf("$%lu = %s\n", (unsigned long)mrdb->print_no++, RSTRING_PTR(s));
+ printf("$%lu = ", (unsigned long)mrdb->print_no++);
+ fwrite(RSTRING_PTR(result), RSTRING_LEN(result), 1, stdout);
+ putc('\n', stdout);
if (mrdb->print_no == 0) {
mrdb->print_no = 1;

Fix that `print` command raises `FrozenError` in `mrdb`; ref 1f5a7f2f

#### Before this patch:

  ```
  $ echo 'p true' | bin/mrdb /dev/null
  (/dev/null:1) mruby application exited.
  FrozenError: can't modify frozen String
  (-:0)
  ```

#### After this patch:

  ```
  $ echo 'p true' | bin/mrdb /dev/null
  (/dev/null:1) $1 = true
  (/dev/null:1)
  ```