Merge branch 'master' into staging

Conflicts:
      pkgs/applications/misc/navit/default.nix
      pkgs/applications/networking/mailreaders/alpine/default.nix
      pkgs/applications/networking/mailreaders/realpine/default.nix
      pkgs/development/compilers/ghc/head.nix
      pkgs/development/libraries/openssl/default.nix
      pkgs/games/liquidwar/default.nix
      pkgs/games/spring/springlobby.nix
      pkgs/os-specific/linux/kernel/perf.nix
      pkgs/servers/sip/freeswitch/default.nix
      pkgs/tools/archivers/cromfs/default.nix
      pkgs/tools/graphics/plotutils/default.nix

pkgs/tools/graphics/plotutils/default.nix

@@ -16,6 +16,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ libpng ];
 
   # disable failing test on i686
+  # https://lists.gnu.org/archive/html/bug-plotutils/2016-04/msg00002.html
   prePatch = stdenv.lib.optionalString stdenv.isi686 ''
     substituteInPlace test/Makefile.in --replace 'spline.test' ' '
   '';