[GHC] #9447: Add support for resizing `MutableByteArray#`s

[GHC]

#9447: Add support for resizing `MutableByteArray#`s
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        Reporter:  hvr               |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D133
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Comment (by bgamari):

 See Phab:D1139 for an implementation of `getSizeofMutableByteArray#`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9447#comment:3>
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