Haiku: remove redundant calls to delete_sem()

Fixes #184.

Semaphores are kernel-managed objects, calling delete_sem() twice is not more
dangerous than calling close() twice on an fd though, it would just return
an error.

src/output/plugins/HaikuOutputPlugin.cxx

@@ -140,9 +140,6 @@ HaikuOutput::Close() noexcept
 
 HaikuOutput::~HaikuOutput()
 {
-	delete_sem(new_buffer);
-	delete_sem(buffer_done);
-
 	finalize_application();
 }