[vala] (18 commits) Non-fast-forward update to branch wip/ci

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/ci' 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:

  baf45d2... coverage: Build gidl-bindings
  87d9d32... ci: Add .gitlab-ci.yml
  a074052... ci: Add ubuntu:16.04 run with gcc
  d3c79c9... ci: Add archlinux:latest run with gcc
  13133b5... ci: Pin archlinux before glibc bump
  ffe1825... ci: Add alpine:edge run with gcc
  f99b0c5... ci: Add fedora:rawhide run with clang
  ec26633... Fedora rawhide is broken
  e9d6f14... ci: Always deploy

Commits added to the branch:

  9bd6528... codegen: Allow null to initialize non-null struct inside in (*)
  75b0117... codegen: Implementing GLib.Source.prepare/check is optional (*)
  7001274... codegen: Fix variadic constructors for compact classes and  (*)
  c258c1d... ccode: Avoid trailing space after #else of CCodeIfSection (*)
  9d7192b... girwriter: Use "optional" and "nullable" instead of depreca (*)
  9a8fd34... build: Use jing to verify generated GIR file, if available (*)
  9d9f640... javascriptcoregtk-4.0: Fix JSC.Class.add_property() binding (*)
  4390860... tests/girwriter: Add missing [Flags] annotation (*)
  75333ea... girwriter: Respect GIR.name for constants, errordomains and (*)
  b3f07f4... coverage: Build gidl-bindings
  e1fcf9e... ci: Add .gitlab-ci.yml
  ccf7e15... ci: Add ubuntu:16.04 run with gcc
  f72f6c2... ci: Add archlinux:latest run with gcc
  2faf940... ci: Pin archlinux before glibc bump
  ccc2fd3... ci: Add alpine:edge run with gcc
  5b6e056... ci: Add fedora:rawhide run with clang
  f683579... Fedora rawhide is broken
  ce1423a... ci: Always deploy

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