eclipse-plugin-cup: use `buildEclipsePlugin`

Since the `buildEclipsePlugin` function now can cope with multiple
plugin JARs we can avoid the workaround used by the cup plugin.

pkgs/applications/editors/eclipse/plugins.nix

···
     };
   };
 
-  cup = buildEclipsePluginBase rec {
+  cup = buildEclipsePlugin rec {
     name = "cup-${version}";
     version = "1.1.0.201604221613";
     version_ = "1.0.0.201604221613";
···
       sha256 = "13nnsf0cqg02z3af6xg45rhcgiffsibxbx6h1zahjv7igvqgkyna";
     };
 
-    srcPlugin1 = fetchurl {
-      url = "http://www2.in.tum.de/projects/cup/eclipse/plugins/CupReferencedLibraries_${version_}.jar";
-      sha256 = "0kif8kivrysprva1pxzajm88gi967qf7idhb6ga2xpvsdcris91j";
-    };
+    srcPlugins = [
+      (fetchurl {
+        url = "http://www2.in.tum.de/projects/cup/eclipse/plugins/CupReferencedLibraries_${version_}.jar";
+        sha256 = "0kif8kivrysprva1pxzajm88gi967qf7idhb6ga2xpvsdcris91j";
+      })
 
-    srcPlugin2 = fetchurl {
-      url = "http://www2.in.tum.de/projects/cup/eclipse/plugins/de.tum.in.www2.CupPlugin_${version}.jar";
-      sha256 = "022phbrsny3gb8npb6sxyqqxacx138q5bd7dq3gqxh3kprx5chbl";
-    };
-
-    srcs = [ srcFeature srcPlugin1 srcPlugin2 ];
+      (fetchurl {
+        url = "http://www2.in.tum.de/projects/cup/eclipse/plugins/de.tum.in.www2.CupPlugin_${version}.jar";
+        sha256 = "022phbrsny3gb8npb6sxyqqxacx138q5bd7dq3gqxh3kprx5chbl";
+      })
+    ];
 
     propagatedBuildInputs = [ zest ];
-
-    phases = [ "installPhase" ];
-
-    installPhase = ''
-      dropinDir="$out/eclipse/dropins/${name}"
-      mkdir -p $dropinDir/features
-      unzip ${srcFeature} -d $dropinDir/features/
-      mkdir -p $dropinDir/plugins
-      cp -v ${srcPlugin1} $dropinDir/plugins/''${srcPlugin1#*-}
-      cp -v ${srcPlugin2} $dropinDir/plugins/''${srcPlugin2#*-}
-    '';
 
     meta = with stdenv.lib; {
       homepage = http://www2.cs.tum.edu/projects/cup/eclipse.php;