[vala] (6 commits) Non-fast-forward update to branch wip/sdl2

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/sdl2' 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:

  d24c6b4... sdl2: Fix a few type problems and cname attribute issues
  3928973... sdl2: Fix cname issues of fields
  227be97... sdl2: Fix static methods
  3f78c7b... sdl2: Fix instance methods
  070a2e7... sdl2: Attribute GL.ContextFlag with Flags
  4a14a56... sdl2: Some more parameter problems and cname attribute issu
  1dfa589... sdl2: Drop superfluous [Compact] attributes
  7d7b6f0... sdl2: More fixes
  c164de6... SDL2_image: Fix issues
  48e8577... SDL2_gfx: Fix issues
  9b514b9... SDL2_mixer: Fix issues
  21446a6... SDL2_net: Fix issues
  f655af5... sdl2: More fixes

Commits added to the branch:

  65f602e... codegen: Correctly retrieve symbol_reference of nested cast (*)
  6c251f9... libvaladoc: Add wrapper for "agedge" of graphviz (*)
  cfc0399... build: Ease source for AC_LANG_SOURCE of CGRAPH check (*)
  8a23e65... codegen: Strip all nested occurances of CCodeCastExpression (*)
  1b81926... codegen: Include <string.h> for memcpy usage in _vala_memdu (*)
  1525da7... sdl2: Fix a couple of binding errors and attribute issues

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