libsexy: remove

People have only been using this for the spell-entry widget, i.e even
hexchat just has the code vendored and are maintaining it themselves.

There is a continuation that could be packaged if anyone needs it
* https://github.com/TingPing/libsexy3
but currently no package within nixpkgs has a use for this.

pkgs/development/libraries/libsexy/default.nix

@@ -1,24 +0,0 @@
-{ stdenv, fetchurl, pkgconfig
-, glib, gtk2, libxml2, pango
-}:
-
-stdenv.mkDerivation {
-  name = "libsexy-0.1.11";
-
-  src = fetchurl {
-    url = http://releases.chipx86.com/libsexy/libsexy/libsexy-0.1.11.tar.gz;
-    sha256 = "8c4101a8cda5fccbba85ba1a15f46f2cf75deaa8b3c525ce5b135b9e1a8fe49e";
-  };
-
-  nativeBuildInputs = [ pkgconfig ];
-
-  buildInputs = [ glib gtk2 libxml2 pango ];
-
-  meta = with stdenv.lib; {
-    description = "A collection of GTK widgets";
-    homepage = https://blog.chipx86.com/tag/libsexy/;
-    license = licenses.lgpl21;
-    maintainers = with maintainers; [ ];
-    platforms = platforms.unix;
-  };
-}