Log Message:
Update to 1.8.6:

1.8.6:

* Documentation:
  - Context::arc(): Fix bug #31345 (Christopher Head) about bad math in arc()
	documentation. (Murray Cumming)
* Build:
  - Cleanup of most -Weffc++ warnings. Bug #28246.
  (Ian Britten)
  - Fix the MSVC build.
  - Added support for Windows 64-bit and Visual Studio 2010.
  (Armin Burgmeier)
  - Fix the 64-bit build.
  (Augusto Jun Devegil)
  - Actually install cairomm-xlib-xrender-1.0.pc.
  (Daisuke Nishikawa)