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/tools/networking/keepalived/default.nix

@@ -26,7 +26,7 @@ stdenv.mkDerivation rec {
  ];
 
   meta = with stdenv.lib; {
-    homepage = http://keepalived.org;
+    homepage = https://keepalived.org;
     description = "Routing software written in C";
     license = licenses.gpl2;
     platforms = platforms.linux;