Fix broken sources.gentoo.org fetch URLs

sources.gentoo.org is deprecated:
https://gitweb.gentoo.org/sites/www.git/commit/_includes/layout/header.html?id=526ebb46632332d44b91e0cc5a517d137845053a

pkgs/development/libraries/dbus-cplusplus/default.nix

@@ -13,8 +13,8 @@ stdenv.mkDerivation rec {
   patches = [
     (fetchurl {
       name = "gcc-4.7.patch";
-      url = "http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/dev-libs/"
-          + "dbus-c%2B%2B/files/dbus-c%2B%2B-0.9.0-gcc-4.7.patch";
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-libs/"
+          + "dbus-c++/files/dbus-c++-0.9.0-gcc-4.7.patch";
       sha256 = "0rwcz9pvc13b3yfr0lkifnfz0vb5q6dg240bzgf37ni4s8rpc72g";
     })
     (fetchurl {

pkgs/development/libraries/xbase/default.nix

@@ -13,15 +13,15 @@ stdenv.mkDerivation rec {
   patches = [
     ./xbase-fixes.patch
     (fetchurl {
-      url = "http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/dev-db/xbase/files/xbase-3.1.2-gcc47.patch?revision=1.1";
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-db/xbase/files/xbase-3.1.2-gcc47.patch?id=0b9005ad4b5b743707922877e5157ba6ecdf224f";
       sha256 = "1kpcrkkcqdwl609yd0qxlvp743icz3vni13993sz6fkgn5lah8yl";
     })
     (fetchurl {
-      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-db/xbase/files/xbase-3.1.2-gcc6.patch";
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-db/xbase/files/xbase-3.1.2-gcc6.patch?id=0b9005ad4b5b743707922877e5157ba6ecdf224f";
       sha256 = "1994pqiip5njkcmm5czb1bg6zdldkx1mpandgmvzqrja0iacf953";
     })
     (fetchurl {
-      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-db/xbase/files/xbase-3.1.2-gcc7.patch";
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/dev-db/xbase/files/xbase-3.1.2-gcc7.patch?id=0b9005ad4b5b743707922877e5157ba6ecdf224f";
       sha256 = "1304gn9dbdv8xf61crkg0fc8cal0h4qkyhlbqa8y618w134cxh1q";
     })
   ];

pkgs/os-specific/linux/shadow/default.nix

@@ -11,7 +11,7 @@ let
     else assert stdenv.hostPlatform.libc == "glibc"; stdenv.cc.libc;
 
   dots_in_usernames = fetchpatch {
-    url = "http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/sys-apps/shadow/files/shadow-4.1.3-dots-in-usernames.patch";
+    url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/sys-apps/shadow/files/shadow-4.1.3-dots-in-usernames.patch";
     sha256 = "1fj3rg6x3jppm5jvi9y7fhd2djbi4nc5pgwisw00xlh4qapgz692";
   };
 

pkgs/tools/archivers/unzip/default.nix

@@ -44,7 +44,7 @@ stdenv.mkDerivation rec {
     })
   ] ++ lib.optional enableNLS
     (fetchurl {
-      url = "http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/app-arch/unzip/files/unzip-6.0-natspec.patch?revision=1.1";
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/app-arch/unzip/files/unzip-6.0-natspec.patch?id=56bd759df1d0c750a065b8c845e93d5dfa6b549d";
       name = "unzip-6.0-natspec.patch";
       sha256 = "67ab260ae6adf8e7c5eda2d1d7846929b43562943ec4aff629bd7018954058b1";
     });

pkgs/tools/misc/bfr/default.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
 
   patches =
     [ (fetchurl {
-        url = "https://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/app-misc/bfr/files/bfr-1.6-perl.patch?revision=1.1";
+        url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/app-misc/bfr/files/bfr-1.6-perl.patch";
         sha256 = "1pk9jm3c1qzs727lh0bw61w3qbykaqg4jblywf9pvq5bypk88qfj";
       })
     ];