Error constructing struct record in member using 'with'

The following code is not compiled:

```
[]
type Person =
{ Name: string; Age: int }
member x.WithAge age =
{ x with Age = age }
```

with the error FS3232: Struct members cannot return the address of fields of the struct by reference, pointing to the `x` inside `WithAge` member.

The problem is that x has type inref, but nothing prevents from constructing another record instance from it.

The known workaround is to declare another variable from `x`:
```
[]
type Person =
{ Name: string; Age: int }
member x.WithAge age =
let copy = x
{ copy with Age = age }
```

Environment:
* .NET Core 2.2
* VS 2019 16.2.5