C# 9 Records: Explicit property declaration breaks primary constructor

**Version Used**: 3.8.0-3.20458.6

**Steps to Reproduce**:

Run the following code:

```
Console.WriteLine (new Test(1).X == 1);

record Test (int X)
{
    int _x;
    public int X { get => _x; init => _x = value; }
}
```

**Expected Behavior**:

This should print "True"

**Actual Behavior**:

It prints "False"

The auto-generated constructor fails to set the X property.
