[ papers ] Comment out petersonsCorrect for performance reasons

On average across 10 runs on an Intel Core i7-8750H with 15.2GB of
available system memory (16GB installed in system), type-checking
`libs/papers/Search/GCL.idr` WITH `petersonsCorrect` takes:

  * 1 minute  48.7 seconds, consuming 3.92GB of RAM

By contrast, commenting `petersonsCorrect` out results in type-checking
taking on average (same #runs, same config):

  * 0 minutes  1.2 seconds, consuming 0.25GB of RAM

And good luck trying to evaluate the thing!
(This might be a good performance test at some point, but uh, we're not
there yet...)

libs/papers/Search/GCL.idr

@@ -332,6 +332,9 @@ checkPetersons = exists $
                       ))
                    tree
 
+{- N.B.: commenting this in causes the type-checking of this file to take ~2
+ -       minutes and ~4 GB of RAM
+ -
 ||| /!\ CAUTION: THIS IS **VERY** SLOW + RESOURCE INTENSIVE /!\
 |||
 ||| Prove that Peterson's Algorithm is a solution to the Critical Section
@@ -350,4 +353,5 @@ petersonsCorrect : Models ? ?
 petersonsCorrect =
   diModels (GCL State, GCL State) State
            (snd (check @{%search} (limit 1000) checkPetersons @{Oh}))
+ -}