[parrot/parrot] 20cb7e: [GH #843] fix unknown -Wno-unused-result

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/parrot/parrot
  Commit: 20cb7e89d7df33d11b795418398b1cfe6888f5ff
      https://github.com/parrot/parrot/commit/20cb7e89d7df33d11b795418398b1cfe6888f5ff
  Author: Reini Urban <rurban at cpanel.net>
  Date:   2012-09-24 (Mon, 24 Sep 2012)

  Changed paths:
    M config/auto/warnings.pm

  Log Message:
  -----------
  [GH #843] fix unknown -Wno-unused-result

Also check overrides for valid warnings.
Use -Wno-parentheses-equality only for clang