[vala] (3 commits) Non-fast-forward update to branch staging

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'staging' 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:

  995060a... vala: Add accessibility check of type for constants and str
  f67a816... vala: Drop SemanticAnalyzer.is_type_accessible()
  2d943cf... vala: Check accessibility of initializer for constant, enum
  12a2361... codegen: Use CCodeConstant for member access of constant sy

Commits added to the branch:

  a0d7177... vala: Add accessibility check of type for constants and str
  1f28a5d... vala: Drop SemanticAnalyzer.is_type_accessible()
  f1a8f2a... codegen: Use CCodeConstant for member access of constant sy