[erlang-patches] Small cleanup of hipe_unified_loader

[Kostis Sagonas]

Cleanup of the file

Consisting of three items:
  - Eliminate uses of is_subtype/2 in specs
  - Change module-local void functions to return 'ok' instead of []
  - Make sure there are no dialyzer warnings with --Wunmatched_returns

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Please include:

   git fetch git://github.com/kostis/otp.git hipe_unified_loader-cleanup

Kostis