Merge recent master into staging

Nixpkgs Hydra: ?compare=1157272

TODO: port e22889064f

Conflicts:
	nixos/tests/gnome3_10.nix (auto-solved)
	pkgs/applications/video/aegisub/default.nix
	pkgs/development/libraries/boost/1.55.nix

pkgs/development/interpreters/guile/default.nix

@@ -27,7 +27,9 @@
   # A native Guile 2.0 is needed to cross-build Guile.
   selfNativeBuildInput = true;
 
-  enableParallelBuilding = true;
+  # Guile 2.0.11 repeatable fails with 8-core parallel building because
+  # libguile/vm-i-system.i is not created in time
+  enableParallelBuilding = false;
 
   patches = [ ./disable-gc-sensitive-tests.patch ./eai_system.patch ./clang.patch ] ++
     (stdenv.lib.optional (coverageAnalysis != null) ./gcov-file-name.patch);