[vala] (25 commits) Non-fast-forward update to branch wip/singleton

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/singleton' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  f2aead1... Add support for singleton object classes

Commits added to the branch:

  a416d04... libusb-1.0: Add some missing symbols (*)
  e96b6ab... vala: Report error for error-domains without any code (*)
  540aa14... parser: Accept "empty" enums/error-domains (*)
  1eae921... gio-2.0: Add custom IOError.from_errno() to make it work as (*)
  df5f39c... tests: Add invalid "empty" enum/errordomain tests to increa (*)
  cb66902... codegen: Don't emit g_type_add_instance_private() in *_regi (*)
  ca34aa6... Revert "codegen: Don't emit g_type_add_instance_private() i (*)
  a96983d... codegen: Move interface_init calls before g_type_add_instan (*)
  08bfe93... codegen: Don't emit g_type_add_instance_private() for dynam (*)
  6cb5427... gtk+-4.0: Update to 3.94.0+bf5f27c6 (*)
  dc999d7... gstreamer: Update from 1.15+ git master (*)
  4f67ef9... gstreamer-rtsp-server-1.0: Update from 1.15+ git master (*)
  3784fdc... manual: Update from wiki.gnome.org (*)
  6e688ba... gtk+-3.0: Update to 3.23.1+5b527d69 (*)
  660b116... gtk+-4.0: Update to 3.94.0+20deda2b (*)
  9a35ed1... gstreamer: Update from 1.15+ git master (*)
  5e727a6... webkit2gtk-4.0: Update to 2.21.5 (*)
  630f4af... glib-2.0: Add Unicode 11.0 symbols (*)
  a5aff19... glib-2.0: Variant.byte() takes an uint8 argument (*)
  bee050d... Revert "codegen: Stop taking explicit references on 'this'  (*)
  b00f917... codegen: Add source_reference to unsupported floating refer (*)
  076df5c... Sync NEWS from 0.40 (*)
  64cca87... Release 0.41.90 (*)
  a62bda1... glib-2.0: Add Array.remove*() wrapper to avoid leaking gene (*)
  b539457... Add support for singleton object classes

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