ART: Topological Sort Traversal Implementation

- Added a topological sort implementation for traversal.
  - Useful for traversals that require traversing the predecessors first.
- Added a function to BasicBlock to detect if it is an exception block.

Change-Id: I573da1768a635c6fd0259573dbb46b112132e129
Signed-off-by: Jean Christophe Beyler <jean.christophe.beyler@intel.com>
Signed-off-by: Razvan A Lupusoru <razvan.a.lupusoru@intel.com>
Signed-off-by: Yixin Shou <yixin.shou@intel.com>
Signed-off-by: Chao-ying Fu <chao-ying.fu@intel.com>
Signed-off-by: Udayan Banerji <udayan.banerji@intel.com>
diff --git a/compiler/dex/pass.h b/compiler/dex/pass.h
index ac22294..4ce040e 100644
--- a/compiler/dex/pass.h
+++ b/compiler/dex/pass.h
@@ -22,6 +22,11 @@
 #include "base/macros.h"
 namespace art {
 
+// Forward declarations.
+struct BasicBlock;
+struct CompilationUnit;
+class Pass;
+
 // Empty Pass Data Class, can be extended by any pass extending the base Pass class.
 class PassDataHolder {
 };