libgcrypt: Disable libcap permission dropping

pkgs/top-level/all-packages.nix

···
   libftdi1 = callPackage ../development/libraries/libftdi/1.x.nix { };
 
   libgcrypt = callPackage ../development/libraries/libgcrypt {
-    libcap = if stdenv.isDarwin then null else pkgs.libcap;
+    # Breaks packages that expect to have elevated privileges
+    # Ex. Lightdm, cryptsetup
+    libcap = null;
   };
 
   libgdiplus = callPackage ../development/libraries/libgdiplus { };