Update swt installation

Permit the installation for x86_64

pkgs/development/libraries/java/swt/default.nix

@@ -6,16 +6,24 @@
 , libsoup
 }:
 
-stdenv.mkDerivation {
-  name = "swt-3.7.2-201202080800";
+let metadata = if stdenv.system == "i686-linux"
+               then { arch = "x86"; sha256 = "10si8kmc7c9qmbpzs76609wkfb784pln3qpmra73gb3fbk7z8caf"; }
+               else if stdenv.system == "x86_64-linux"
+                    then { arch = "x86_64"; sha256 = "0hq48zfqx2p0fqr0rlabnz2pdj0874k19918a4dbj0fhzkhrh959"; }
+                    else { };
+in stdenv.mkDerivation rec {
+  version = "3.7.2";
+  fullVersion = "${version}-201202080800";
+  name = "swt-${version}";
+
   builder = ./builder.sh;
 
   # Alas, the Eclipse Project apparently doesn't produce source-only
   # releases of SWT.  So we just grab a binary release and extract
   # "src.zip" from that.
   src = fetchurl {
-    url = "http://archive.eclipse.org/eclipse/downloads/drops/R-3.7.2-201202080800/swt-3.7.2-gtk-linux-x86.zip";
-    sha256 = "10si8kmc7c9qmbpzs76609wkfb784pln3qpmra73gb3fbk7z8caf";
+    url = "http://archive.eclipse.org/eclipse/downloads/drops/R-${fullVersion}/${name}-gtk-linux-${metadata.arch}.zip";
+    sha256 = metadata.sha256;
   };
 
   buildInputs = [unzip jdk pkgconfig gtk libXtst libXi mesa webkit libsoup];