[vala] (4 commits) Non-fast-forward update to branch wip/issue548

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/issue548' 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:

  46f3858... vala: Don't just guess and check for a matching base_interf
  952fa99... vala: Search in all interfaces for an implementation match 

Commits added to the branch:

  2471bae... vala: Allow null-type as intializer for static struct field (*)
  b5d3e0f... codegen: Emit initializer for enum-value into wanted declar (*)
  f9006a1... vala: Don't just guess and check for a matching base_interf
  c2836ca... vala: Search in all interfaces for an implementation match 

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