io-sim: backport masking state fix

Apply the fix from the commit 69d793a73 to `IOSimPOR`.

Author: coot

io-sim/src/Control/Monad/IOSimPOR/Internal.hs

@@ -591,8 +591,7 @@ schedule thread@Thread{
     ThrowTo e tid' _ | tid' == tid -> do
       -- Throw to ourself is equivalent to a synchronous throw,
       -- and works irrespective of masking state since it does not block.
-      let thread' = thread { threadControl = ThreadControl (Throw e) ctl
-                           , threadMasking = MaskedInterruptible }
+      let thread' = thread { threadControl = ThreadControl (Throw e) ctl }
       trace <- schedule thread' simstate
       return (SimTrace time tid tlbl (EventThrowTo e tid) trace)
 
@@ -631,7 +630,6 @@ schedule thread@Thread{
                                      threadVClock  = vClock' } =
                 t { threadControl = ThreadControl (Throw e) ctl'
                   , threadBlocked = False
-                  , threadMasking = MaskedInterruptible
                   , threadVClock  = vClock' `leastUpperBoundVClock` vClock }
               simstate'@SimState { threads = threads' }
                          = snd (unblockThreads vClock [tid'] simstate)