[GHC] #15131: Speed up certain Foldable NonEmpty methods

[GHC]

#15131: Speed up certain Foldable NonEmpty methods
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Core Libraries    |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4677
       Wiki Page:                    |
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Comment (by dfeuer):

 Yours has to hold on to the "and then add one" while calculating the
 length of the list. Same goes for `max` and `min`. I'll look more later.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15131#comment:3>
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