the function _vsnprintf_output returns bad count.

[mazhenke]

in function _vsnprintf_output from:lib/libc/printf.c

static int _vsnprintf_output(const char *str, size_t len, void *state)
{
struct _output_args *args = state;

size_t count = 0;
while (count < len) {
    if (args->pos < args->len) {
        args->outstr[args->pos++] = *str;
    }

    str++;
    count++;
}

return count;

}

the return value count couldn't represent the actual length of string const char *str.