add libevent

svn path=/nixpkgs/trunk/; revision=6678

pkgs/development/libraries/libevent/default.nix

@@ -0,0 +1,10 @@
+{stdenv, fetchurl}:
+
+stdenv.mkDerivation {
+  name = "libevent-1.1b";
+
+  src = fetchurl {
+    url = http://monkey.org/~provos/libevent-1.1b.tar.gz;
+    md5 = "ec8dac612aa43ed172f300f396fcec49";
+  };
+}