add a couple of missing notices

Author: dnolen

src/main/cljs/cljs/externs.js

@@ -1,3 +1,13 @@
+/**
+ * Copyright (c) Rich Hickey. All rights reserved.
+ * The use and distribution terms for this software are covered by the
+ * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+ * which can be found in the file epl-v10.html at the root of this distribution.
+ * By using this software in any fashion, you are agreeing to be bound by
+ * the terms of this license.
+ * You must not remove this notice, or any other, from this software.
+ */
+
 Math.imul = function(a, b) {};
 
 Object.prototype.done;

src/main/cljs/cljs/imul.js

@@ -1,3 +1,15 @@
+/**
+ * Copyright (c) Rich Hickey. All rights reserved.
+ * The use and distribution terms for this software are covered by the
+ * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+ * which can be found in the file epl-v10.html at the root of this distribution.
+ * By using this software in any fashion, you are agreeing to be bound by
+ * the terms of this license.
+ * You must not remove this notice, or any other, from this software.
+ */
+
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/imul
+
 if(typeof Math.imul == "undefined" || (Math.imul(0xffffffff,5) == 0)) {
     Math.imul = function (a, b) {
         var ah  = (a >>> 16) & 0xffff;