formattedRead: %*d and %d should read the same

[dlangBugzillaToGithub]

bugzilla (@berni44) reported this on 2019-11-14T18:14:48Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=20392

Description

This throws an exception:

---
import std.format;

void main()
{
    string str = "foo bar buzz";
    string a, c;
    int b;
    formattedRead(str, "%s %d %s", &a, &b, &c);
}
---

This not:

---
import std.format;

void main()
{
    string str = "foo bar buzz";
    string a, c;
    formattedRead(str, "%s %*d %s", &a, &c);
}
---

The reason is, that %*d accepts an empty string as a number while %d doesn't.