message: cxx.boost: Expose __prefer_shared.
diff: @@ -140,6 +140,10 @@ class Boost(drake.Configuration):
  (version, self._format_search([path for path, include_subdir in prefixes]),
  ', '.join(map(str, miss))))
  + @property
  + def prefer_shared(self):
  + return self.__prefer_shared
  +
  def __find_lib(self, lib, lib_path, cxx_toolkit, static):
  # Suffixes
  suffixes = ['-mt', '']
  