Changed ObjectSpace.define_finalizer call to be ruby 1.9.2 compatible…

…. There should probably be a Ruby

version test to make it compatible with both 1.8 and 1.9. Had to update spec to call GC.start to
get it to pass on Mac - didn't need it on Linux.

lib/tlattr_accessors.rb

@@ -35,7 +35,7 @@ def #{name}=(val)
           #{ivar} = Hash.new #{'{|h, k| h[k] = val}' if first_is_default} unless #{ivar}
           thread_id = Thread.current.object_id
           unless #{ivar}.has_key?(thread_id)
-            ObjectSpace.define_finalizer(Thread.current, lambda { #{ivar}.delete(thread_id) })
+            ObjectSpace.define_finalizer(Thread.current, proc {|id| #{ivar}.delete(thread_id) })
           end
           #{ivar}[thread_id] = val
         end

spec/thread_local_accessors_spec.rb

@@ -69,6 +69,7 @@ def initialize(value)
         x.bar = Bar.new(rand)
       end.join
     end
+    GC.start
     hash = x.send :instance_variable_get, '@_tlattr_bar'
     hash.size.should < (n / 2) # it should be a lot lower than n!
   end