suggest on mimalloc stats

Nobody has claimed this yet.

as a mimalloc big fans, i want to stat the current value, like

* the current segments i used
* the current memory i allocated
* the current pages i used
* ...
```
static void mi_stat_print(const mi_stat_count_t* stat, const char* msg, int64_t unit, mi_output_fun* out ) {
_mi_fprintf(out,"%10s:", msg);
if (unit>0) {
mi_print_amount(stat->peak, unit, out);
mi_print_amount(stat->allocated, unit, out);
mi_print_amount(stat->freed, unit, out);
mi_print_amount(unit, 1, out);
mi_print_count(stat->allocated, unit, out);
if (stat->allocated > stat->freed)
_mi_fprintf(out, " not all freed!\n");
else
_mi_fprintf(out, " ok\n");
}
else if (unit<0) {
mi_print_amount(stat->peak, -1, out);
mi_print_amount(stat->allocated, -1, out);
mi_print_amount(stat->freed, -1, out);
if (unit==-1) {
_mi_fprintf(out, "%22s", "");
}
else {
mi_print_amount(-unit, 1, out);
mi_print_count((stat->allocated / -unit), 0, out);
}
if (stat->allocated > stat->freed)
_mi_fprintf(out, " not all freed!\n");
else
_mi_fprintf(out, " ok\n");
}
else {
mi_print_amount(stat->peak, 1, out);
mi_print_amount(stat->allocated, 1, out);
_mi_fprintf(out, "\n");
}
}
```

Start by locating mi_stat_print and reading how the existing statistics are collected and exposed. Determine how the requested current segments, allocated memory, pages, and related values should be represented and accessed. Done means the requested current mimalloc statistics can be obtained consistently.

Written by the indexing model from the issue text.