message: cmake: do not play with MACOSX_DEPLOYMENT_TARGET
  Leave it as it is.
diff: @@ -25,11 +25,6 @@ class CMakeBuilder(drake.Builder):
  'CXX': self.toolkit.cxx,
  })
  self.__cmake_cache = drake.node('CMakeCache.txt')
  - mdt = self.__env.get('MACOSX_DEPLOYMENT_TARGET', None)
  - # cmake sets the appropriate -isysroot depending on MACOSX_DEPLOYMENT_TARGET
  - # but the STL in SDKS prior to 10.9 are not cxx11 compliant (no std::unique_ptr)
  - if mdt and (mdt == '10.7'or mdt == '10.8'):
  - self.__env['MACOSX_DEPLOYMENT_TARGET'] = '10.9'
  self.__targets = targets
  # cmake 3 compat
  self.__vars.update({'CMAKE_SYSTEM_PROCESSOR': 'x86_64'})
  