Decide which is the correct default refinement for GHC.Num and GHC.Real./

According to this piece of code in findAndParseSpecFiles, the Real.spec is loaded by default, unless the --linear flag is explicitly set (the default is linear = False, though):

  patSpec  <- liftIO $ getPatSpec  modGraph paths $ totalityCheck cfg
  rlSpec   <- liftIO $ getRealSpec modGraph paths $ not (linear cfg)
-- and later on
...
getRealSpec :: ModuleGraph -> S.HashSet FilePath -> Bool -> IO [FilePath]
getRealSpec modGraph paths freal
  | freal     = moduleFiles modGraph Spec paths [realSpecName]
  | otherwise = moduleFiles modGraph Spec paths [notRealSpecName]
  where
    realSpecName    = "Real"
    notRealSpecName = "NotReal"

@nikivazou found this surprising, as she thought the correct default was NotReal instead. We should review what we are doing here to be sure we are doing the right thing.

Start in src/Language/Haskell/Liquid/GHC/Interface.hs at findAndParseSpecFiles and getRealSpec, then inspect how the --linear setting selects Real or NotReal. Compare the two refinement files and existing uses of the default to determine which behavior is correct; done means the default choice is resolved and the issue's requested correction is identified.