timeout.rb: freeze a string message

* lib/timeout.rb (Timeout#timeout): freeze a string message to
  reduce string allocations.  [Fix GH-996]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51566 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Thu Aug 13 22:49:42 2015  Juanito Fatas  <katehuang0320@gmail.com>
+
+	* lib/timeout.rb (Timeout#timeout): freeze a string message to
+	  reduce string allocations.  [Fix GH-996]
+
 Thu Aug 13 17:42:34 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_core.h (rb_call_info_kw_arg_bytes): move the definition

lib/timeout.rb

@@ -71,7 +71,7 @@ module Timeout
   # a module method, so you can call it directly as Timeout.timeout().
   def timeout(sec, klass = nil)   #:yield: +sec+
     return yield(sec) if sec == nil or sec.zero?
-    message = "execution expired"
+    message = "execution expired".freeze
     e = Error
     bl = proc do |exception|
       begin