treewide: update homepages to https where available

Based on "problems" from repology:

https://repology.org/repository/nix_unstable/problems

Mostly simple changes to reflect redirects.

pkgs/development/libraries/libgpod/default.nix

@@ -30,7 +30,7 @@ in stdenv.mkDerivation rec {
     ++ lib.optionals monoSupport [ mono gtk-sharp-2_0 ];
 
   meta = {
-    homepage = http://gtkpod.sourceforge.net/;
+    homepage = https://gtkpod.sourceforge.net/;
     description = "Library used by gtkpod to access the contents of an ipod";
     license = "LGPL";
     platforms = stdenv.lib.platforms.gnu ++ stdenv.lib.platforms.linux;