Merge pull request #8 from ms-ati/fix-cond-var-signal-when-no-waiters

Fix ConditionVariable#signal to only post if semaphore has waiters

lib/process_shared/condition_variable.rb

@@ -16,7 +16,9 @@ module ProcessShared
     end
 
     def signal
-      @sem.post
+      @internal.synchronize do
+        @sem.post unless @waiting.read_int.zero?
+      end
     end
 
     def wait(mutex, timeout = nil)