Fix CountTableRef#getOrDefault
Fix CountTableRef#getOrDefault

Fixes issue with CountTableRef and getOrDefault:
```{nimrod}
import tables

proc main() =
  const testKey = "TESTKEY"
  let t: CountTableRef[string] = newCountTable[string]()

  # Before, does not compile with error message:
  #test_counttable.nim(7, 43) template/generic instantiation from here
  #lib/pure/collections/tables.nim(117, 21) template/generic instantiation from here
  #lib/pure/collections/tableimpl.nim(32, 27) Error: undeclared field: 'hcode'

  echo "Count of " & testKey & " is " & $t.getOrDefault(testKey)
  t.inc(testKey,3)
  echo "Count of " & testKey & " is " & $t.getOrDefault(testKey)

when isMainModule:
  main()
```

Previously, `getOrDefault` for CountTableRef objects was calling the
`getOrDefaultImpl` template, which used the t.data.hcode object -
assuming a Table or similar object.  Because CountTableRef didn't have
an hcode in its data tuples, this wouldn't compile.  Changed to be the
same as `CountTable#getOrDefault`.

singularperturbation/Nim,jfhg/Nim,jfhg/Nim,singularperturbation/Nim,dom96/Nim,haiodo/Nim,russpowers/Nim,jfhg/Nim,singularperturbation/Nim,mbaulch/Nim,haiodo/Nim,singularperturbation/Nim,jsanjuas/Nim,haiodo/Nim,endragor/Nim,russpowers/Nim,endragor/Nim,zachaysan/Nim,mbaulch/Nim,haiodo/Nim,russpowers/Nim,jsanjuas/Nim,jsanjuas/Nim,endragor/Nim,jsanjuas/Nim,endragor/Nim,dom96/Nim,mbaulch/Nim,mbaulch/Nim,jfhg/Nim,russpowers/Nim,dom96/Nim,haiodo/Nim,russpowers/Nim,tulayang/Nim,jsanjuas/Nim,mbaulch/Nim,tulayang/Nim,russpowers/Nim,tulayang/Nim,russpowers/Nim,jfhg/Nim,tulayang/Nim,dom96/Nim,zachaysan/Nim,mbaulch/Nim,mbaulch/Nim,singularperturbation/Nim,jfhg/Nim,dom96/Nim,tulayang/Nim,endragor/Nim,jsanjuas/Nim,zachaysan/Nim,tulayang/Nim,endragor/Nim,singularperturbation/Nim,haiodo/Nim,jfhg/Nim,singularperturbation/Nim,dom96/Nim,haiodo/Nim,dom96/Nim,jsanjuas/Nim,zachaysan/Nim,zachaysan/Nim,endragor/Nim,zachaysan/Nim,zachaysan/Nim