libitm: Truncate undo log after rolling back.

	libitm/
	* local.cc (GTM::gtm_undolog::rollback): Truncate undo log after
	rolling back.
	* containers.h (GTM::vector::set_size): New.

From-SVN: r183173
diff --git a/libitm/containers.h b/libitm/containers.h
index 394b6f2..3690565 100644
--- a/libitm/containers.h
+++ b/libitm/containers.h
@@ -92,6 +92,7 @@
   size_t size() const { return m_size; }
   size_t capacity() const { return this->capacity; }
 
+  void set_size (size_t size) { m_size = size; }
   void clear() { m_size = 0; }
 
   iterator push() {