[GHC] #10223: Cleanup `mk/build.mk.sample`

[GHC]

#10223: Cleanup `mk/build.mk.sample`
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        Reporter:  thomie            |                   Owner:  thomie
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by Thomas Miedema <thomasmiedema@…>):

 In [changeset:"3749c05216339df60e1ffbb28c8b957ad5020b00/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="3749c05216339df60e1ffbb28c8b957ad5020b00"
 Reformat build flavours in build.mk.sample (#10223)

 Use same format for each build flavour, to make it easier to compare
 them. Refactoring only.

 Reviewed By: austin

 Differential Revision: https://phabricator.haskell.org/D782
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10223#comment:3>
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