[libqb/f15] (4 commits) ...Rebase to upstream 0.5.1

[Angus Salkeld]

Summary of changes:

  51f257a... Initial import (#668243). (*)
  e754ff2... Update libqb to 0.5.0 (*)
  d467e32... Rebase to new upstream minor release 0.5.0 -> 0.5.1 (*)
  1255287... Rebase to upstream 0.5.1

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