Log Message:
Update to 2.2.2:

2.2.2 (stable)

* Added an include of functors/slot.h that was mistakenly removed
  during the 2.1 series.
  (Deng Xiyue) Bug #521418.

2.2.1 (stable):

* Really fix the build with Sun CC.
  (Elaine Xiong. Bug #302098)

2.2.0 (stable):

* Build fixes when using gcc 4.3 pre-releases.
  (Ryan Hill, Vladimir Marek)