ninja-custom-command-depends
----------------------------

* The :command:`add_custom_command` command gained a new
  ``DEPENDS_EXPLICIT_ONLY`` option to tell the :ref:`Ninja Generators`
  not to add any dependencies implied by the target to which it is
  attached.

* The :variable:`CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY` variable can
  be set to enable ``DEPENDS_EXPLICIT_ONLY`` in all uses of
  :command:`add_custom_command` command.