message: cxx: Improve CLI arguments descriptions.
diff: @@ -562,6 +562,9 @@ class _ToolkitType(type):
  class Toolkit(metaclass = _ToolkitType):
  + def __drake_configure_describe__(self):
  + return 'compiler-path'
  +
  def __init__(self):
  self.includes = []
  self._hook_object_deps = []
  @@ -590,6 +593,7 @@ class Toolkit(metaclass = _ToolkitType):
  def hook_bin_src(self):
  return self._hook_bin_src
  +
  class GccToolkit(Toolkit):
  class Kind(drake.Enumerated,
  @@ -2078,6 +2082,9 @@ class LibraryConfiguration(drake.Configuration):
  """Configuration for a classical C/C++ library."""
  + def __drake_configure_describe__(self):
  + return '{}-prefix'.format(self.__name__)
  +
  def __init__(self, token = None, name = None, prefix = None,
  include_dir = None, libs = None,
  toolkit = None):
  