Fix historyHook memory leak

updateHistory leaks unfiltered windows from previous states as it is never
forced. The consumer of such data structure is not visible to ghc, so the
demand analysis has to fallback on pure laziness.

We fix this inserting evaluation points on the `historyHook` function. We do
this for two reasons, this is the only function calling `updateHistory`.
Plus we cannot do it clearly at the `updateHistory` function as we operate
inside a continuation on withWindowSet. In respect to the `put`, everything
would be a big thunk.

xmonad-contrib.cabal

@@ -61,7 +61,8 @@ library
                    unix,
                    X11 >= 1.10 && < 1.11,
                    xmonad >= 0.16.99999 && < 0.18,
-                   utf8-string
+                   utf8-string,
+                   parallel
     default-language: Haskell2010
 
     cpp-options:   -DXMONAD_CONTRIB_VERSION_MAJOR=0
@@ -448,6 +449,7 @@ test-suite tests
                , process
                , unix
                , utf8-string
+               , parallel
                , xmonad >= 0.16.9999 && < 0.18
   cpp-options: -DTESTING
   ghc-options: -Wall -Wno-unused-do-bind