getAst: static int is rkNone within called macro scope
When using getAst to capture a macro output, static int have no values.
The error is `Error: opcAsgnInt: got rkNone`

Test case:

```Nim
import macros

macro ccopy2[N: static int](a0: var array[N, uint64], b0: array[N, uint64], ctl0: uint64): untyped =

  echo N # This has value rkNone in getAst, comment this out and it "works"

  result = quote do:
    if `ctl0` != 0:
      for i in 0 ..< `N`: # The N disappears in `toStrLit`
        `a0`[i] = `b0`[i]

macro capture_macro_lit2[N: static int](a1: var array[N, uint64], b1: array[N, uint64], ctl1: uint64): untyped =
  result = newStmtList()
  let ast = getAst(ccopy2(a1, b1, ctl1))

  result.add ast.toStrLit()

proc capture_macro_str2(): string =
  var a, b: array[2, uint64]
  var ctl: uint64
  capture_macro_lit2(a, b, ctl)

echo capture_macro_str2()
```