Merge remote-tracking branch 'origin/master' into multiple-outputs

Conflicts:
	pkgs/development/libraries/acl/default.nix
	pkgs/development/libraries/atk/2.6.x.nix
	pkgs/development/libraries/attr/default.nix
	pkgs/development/libraries/cairo/default.nix
	pkgs/development/libraries/freetype/default.nix
	pkgs/development/libraries/glib/2.34.x.nix
	pkgs/development/libraries/gtk+/2.24.x.nix
	pkgs/development/libraries/libtiff/default.nix
	pkgs/development/libraries/openssl/default.nix
	pkgs/development/libraries/pango/1.30.x.nix
	pkgs/misc/cups/default.nix
	pkgs/os-specific/linux/util-linux/default.nix
	pkgs/servers/x11/xorg/builder.sh
	pkgs/servers/x11/xorg/default.nix
	pkgs/top-level/all-packages.nix