Update homepage attributes: http -> https

Homepage link "http://.../" is a permanent redirect to "https://.../" and should be updated
https://repology.org/repository/nix_stable/problems

pkgs/misc/drivers/gutenprint/default.nix

@@ -44,7 +44,7 @@ stdenv.mkDerivation rec {
 
   meta = with stdenv.lib; {
     description = "Ghostscript and cups printer drivers";
-    homepage = http://sourceforge.net/projects/gimp-print/;
+    homepage = https://sourceforge.net/projects/gimp-print/;
     license = licenses.gpl2;
     platforms = platforms.linux;
   };

pkgs/misc/emulators/higan/default.nix

@@ -77,7 +77,7 @@ stdenv.mkDerivation rec {
         - NEC's PC Engine, SuperGrafx;
         - Bandai' WonderSwan, WonderSwan Color.
     '';
-    homepage = http://byuu.org/higan/;
+    homepage = https://byuu.org/higan/;
     license = licenses.gpl3Plus;
     maintainers = with maintainers; [ AndersonTorres ];
     platforms = with platforms; unix;

pkgs/misc/emulators/retroarch/cores.nix

@@ -33,7 +33,7 @@ let
 
     meta = with stdenv.lib; {
       inherit description;
-      homepage = http://www.libretro.com/;
+      homepage = https://www.libretro.com/;
       license = licenses.gpl3Plus;
       maintainers = with maintainers; [ edwtjo hrdinka MP2E ];
       platforms = platforms.linux;

pkgs/misc/ghostscript/default.nix

@@ -105,7 +105,7 @@ stdenv.mkDerivation rec {
   passthru = { inherit version; };
 
   meta = {
-    homepage = http://www.ghostscript.com/;
+    homepage = https://www.ghostscript.com/;
     description = "PostScript interpreter (mainline version)";
 
     longDescription = ''

pkgs/misc/themes/blackbird/default.nix

@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
 
   meta = {
     description = "Dark Desktop Suite for Gtk, Xfce and Metacity";
-    homepage = http://github.com/shimmerproject/Blackbird;
+    homepage = https://github.com/shimmerproject/Blackbird;
     license = with stdenv.lib.licenses; [ gpl2Plus cc-by-nc-sa-30 ];
     platforms = stdenv.lib.platforms.linux;
     maintainers = [ stdenv.lib.maintainers.romildo ];