Struct member access inside quotation gives compile error

Acccessing members of a _struct_ captured local variable gives spurious "A quotation may not involve an assignment to or taking the address of a captured local variable" errors.

#### Repro steps

```fsharp
open FSharp.Quotations

[]
type S =
{
A : int
}

let go () =
let s = { A = 1 }
<@ s.A @>
```

#### Expected behavior

`go` should compile.

#### Actual behavior

`go` gives a compile error (squiggly is under `s` in the quotation) of "A quotation may not involve an assignment to or taking the address of a captured local variable"

Some further examples of quotations that do / don't work:
```fsharp

open FSharp.Quotations

[]
type S =
{
A : int
}
with
member __.B () = 1
member __.C () () = 2

let go () =
let s = { A = 1 }

// # these do not compile if `S` is a struct

// Accessing a field of `S`
let e = <@ s.A @>

// Invoking a member method of `S`
let e = <@ s.B () @>

// # these compile regardless of `S` being a struct

// Accessing a member method of `S`
let e = <@ s.B @>
let e = <@ s.C @>

// Invoking a curried member method of `S`
let e = <@ s.C () @>
let e = <@ s.C () () @>

// Invoking a member method of `S` by accessing it then using a lambda to invoke it
let e = <@ (fun f -> f ()) s.B @>

// Accessing a field of `S` via splicing
let sExpr = <@ s @>
let e = <@ (%sExpr).A @>

// Invoking a member method of `S` via splicing
let e = <@ (%sExpr).B () @>

()
```

#### Known workarounds

No known workarounds.

#### Related information

* Windows
* .NET Framework 4.6.1 and Core 2.0 tested - possibly others