[retro-gtk] (8 commits) ...core: Check controller in retro_core_set_controller()

[Adrien Plazas <aplazas src gnome org>]

Summary of changes:

  ffe2d9f... core: Document the iterated signal (*)
  d1a691b... core: Improve the runahead property documentation (*)
  388e1d7... core: Typo, quote and apostrophe fix (*)
  9d81cae... core: Fix a precondition in retro_core_override_option_defa (*)
  2a7abec... core: Make keyboard_widget_notify() static (*)
  349e254... core: Make controller_state_changed_cb() static (*)
  b935f18... core: Check controller in retro_core_set_default_controller (*)
  7bb2f2f... core: Check controller in retro_core_set_controller() (*)

(*) This commit already existed in another branch; no separate mail sent